TS Inter Maths 1B Concept

maths IB feature image head

 This note is designed by the ‘Basics in Maths’ team. These notes to do help the TS intermediate first-year Maths students fall in love with mathematics and overcome the fear.

These notes cover all the topics covered in the TS I.P.E  first year maths 1B syllabus and include plenty of formulae and concept to help you solve all the types of Inter Math problems asked in the I.P.E and entrance examinations.

0.COORDINATE GEOMETRY( BASICS)

  • Distance between two points A(x1, y1), B(x2, y2) is 

distance between two points

  • distance between a point A(x1, y1) to the origin is

distance between a point and origin

  • The midpoint of two points A(x1, y1), B(x2, y2) is

  •     If P divides the line segment joining the points A(x1, y1), B(x2, y2) in the ratio m:n then the coordinates of P are

section formula

  • Area of the triangle formed by the vertices A (x1, y1), B (x2, y2) and C (x3, y3) is


1. LOCUS

   Locus: The set of points which are satisfying a given condition or property is called locus of the point.

Ex:- If a point P is equidistance from the points A and B, then AP =BP

locus 1Ex 2: – set of points which are at a constant distance from a fixed point. circle for locus

here the locus of a point is a circle.

• In a right-angled triangle PAB, the right angle at P and P is the locus of the point, then

AB2 = PA2 + PB2

right- angled triangle

•Area of the triangle formed by the vertices A (x1, y1), B (x2, y2) and C (x3, y3) is


2.CHANGE OF AXES

Transformation of axes:

When  the origin is shifted to  (h, k), without changing the direction of axes then


transformation of axes

•To remove the first degree terms of the equation ax2  + 2hxy + by2 +2gx +2fy+ c = 0, origin should be shifted to the point    formula 1

•If the equation ax2 + by2 +2gx +2fy+ c = 0, origin should be shifted to the point  TS inter 1B change of axes 1

Rotation of axes:

When the  axes are rotated through an angle θ then

rotation-of-axes-diagram.j

rotation of axes

•To remove the xy term of the equation ax2 + 2hxy + by2  = 0, axes should be rotated through an angle θ is given by 

formula 2


3.STRAIGHT LINES

Slope:-  A-line makes an angle θ with the positive direction of the X-axis, then tan θ is called the slope of the line.

              It is denoted by “m”.  slope - diagram

 m= tanθ

• The slope of the x-axis is zero.

• Slope of any line parallel to the x-axis is zero.

• The y-axis slope is undefined.

• The slope of any line parallel to the y-axis is also undefined.

• The slope of the line joining the points A (x1, y1) and B (x2, y2) is

slope formula 1Slope of the line ax + by + c = 0 is  s inter slope of the straight line

Types of the equation of a straight line:

  • Equation of x- axis is y = 0.
  • Equation of any line parallel to the x-axis is y = k, where k is the distance from above or below the x-axis.
  • Equation of y- axis is x = 0.
  • Equation of any line parallel to y-axis is x = k, where k is the distance from the left or right side of the y-axis.

Slope- intercept form

The equation of the line with slope m and y-intercept c is y = mx + c.

Slope point form:

The equation of the line passing through the point (x1, y1) with slope m is

y – y1 = m (x – x1)

Two points form:

The equation of the line passing through the points (x1, y1) and (x2, y2) ’ is

equation of the line two

Intercept form:

The equation of the line with x-intercept a, y-intercept b is

equation of the line in the intercept form

intercept form

• The equation of the line ∥ el    to ax +by + c = 0 is ax +by + k = 0.

• The equation of the line ⊥ler   to ax +by + c = 0 is bx −ay + k = 0.

Note: –

  1. If two lines are parallel then their slopes are equal

m1 = m2

  1. If two lines are perpendicular then product of their slopes is – 1

m1 × m2 = – 1

  1. The area of the triangle formed by the line ax + by + c = 0 with the coordinate axes is TS inter 1B Straight lines 2
  2. The area of the triangle formed by the line  TS inter 1B Straight lines 4 with the coordinate axes is  TS inter 1B Straight lines 3

Perpendicular distance (Length of the perpendicular):

The perpendicular distance from a point P (x1, y1) to the line ax + by + c = 0 is

 Perpendicular distance (Length of the perpendicular): The perpendicular distance from a point P (x1, y1) to the line ax + by + c = 0 is

• The perpendicular distance from origin to the line ax + by + c = 0 is  TS inter 1B Straight lines 5

Distance between two parallel lines:

•The distance between the parallel lines ax1 + by1 + c1 = 0 and ax2 + by2 + c2 = 0 is

distance between parallel lines

Perpendicular form or Normal form:

    The equation of the line which is at a distance of ‘p’ from the origin and α (0≤ α ≤ 3600) is the angle made by the perpendicular with normal formthe positive direction of the x-axis is x cosα + y sinα = p.

 

 

 

Symmetric form:

The equation of the line passing through point P (x1, y1) and having inclination θ is

symmetric form

Parametric form:

if P (x, y) is any point on the line passing through A (x1, y1) and

making inclination θ, then                                                                                              parametric form

x = x1 + r cos θ, y = y1 + r sin θ

where ‘r’  is the distance from P to A.

• The ratio in which the line L ≡ ax + by + c = 0 divide the line segment joining the points A (x1, y1), B (x2, y2) is – L11: L22.

Where L11 = ax1 + by1 + c and L22 = ax2 + by2 + c.

Note: – the points A (x1, y1), B (x2, y2) lie on the same side or opposite side of line L = 0 according to L11 and L22 have the same sign or opposite sign.

∗  x-axis divides the line segment joining the points A (x1, y1), B (x2, y2) in the ratio – y1: y2.

∗  y-axis divides the line segment joining the points A (x1, y1), B (x2, y2) in the ratio – x1: x2.

Point of intersection of two lines:

the point of intersection of two lines a1x + b1y + c = 0 and a2x + b2y + c = 0 is

poin of intersection of two lines

 

Concurrent Lines:                concurrent lines

Three or more lines are said to be concurrent lines if they have a point in common.

The common point is called the point of concurrence.

∗  The condition that the lines a1x + b1y + c1 = 0, a2x + b2y + c2 = 0 and a3x + b3y + c3 = 0 to be concurrent is

a3(b1c2 – b2c1) + b3(c1a2 – c2a1) + c3(a1b2 – a2b1).

∗ The condition that the lines ax + hy +g = 0, hx + by + f = 0 and gx +fy + c = 0 is

abc + 2fgh – af2 – bg2 – ch2 = o.

Note: – if two lines a1x + b1y + c1 = 0 and a2x + b2y + c2 = 0 said to be identical (same) if TS inter 1B Straight lines 6

Family of a straight line:

Family of straight lines: – A set of straight lines having a common property is called a family of straight lines.

Let L1 ≡ a1x + b1y + c1 = 0 and L2 ≡ a2x + b2y + c2 =0 represent two intersecting lines, theThe equation λ1 L1 + λ2 L2 = 0 represent a family of straight lines passing through the point of intersection of the lines L1 = 0 and L2 = 0.

∗  The equation of the straight line passing through the point of intersection of the lines L1 = 0 and L2 = 0 is L1 + λL2 = 0.

The angle between two lines:

If θ is the angle between the lines a1x + b1y + c1 = 0 and a2x + b2y + c2 = 0 then

angle between two lines

∗  If θ is an acute angle then

acute angle between two lines

∗ If θ is the angle between two lines, then (π – θ) is another angle between two lines.

∗ If θ≠π/2 is angle between the lines a1x + b1y + c1 = 0 and a2x + b2y + c2 = 0, then

angle between two lines using tanѳ

∗ If m1, m2 are the slopes of two lines then

angle between two lines when slopes are given

Note: – The lines a1x + b1y + c1 = 0 and a2x + b2y + c2 = 0 are

∗ Parallel iff  TS inter 1B Straight lines 7

∗ Perpendicular iff a1a2 + b1b2 = 0

The foot of the perpendicular:

If Q (h. k) is the foot of the perpendicular from a point P (x1, y1)to the line ax + by +c = 0 then    oot of the perpendicular diagram

foot of the perpendicular

 

 

 

 

 

Image of the point:

If Q (h. k) is the image of point P (x1, y1)   with respect to the line ax + by +c = 0 then         image of the point diagram

image of the point 1

 

 

 

 

 

 

 

 

Collinear Points:

If three points are said to be collinear, then they lie on the same line.

∗ If A, B, and C are collinear, then

Slope of AB = Slope of BC (or) Slope of BC = Slope of AC (or) Slope of AB = Slope of AC


4. PAIR OF STRAIGHT LINES

∎ ax2 + 2hxy + by2 = 0 is called the second-degree homogeneous equation in two variable x and y.

This equation always represents a pair of straight lines which are passing through the origin.

∎ If l1x + m1y = 0 and l2x + m2y = 0 are two lines represented by the equation ax2 + 2hxy + by2 = 0, then ax2 + 2hxy + by2 = (l1x + m1y) (l2x + m2y)

⇒ a = l1l2; 2h = l1m2 + l2m1; b = m1m2

∎ If m1, m2 are the slopes of the lines represented by the equation ax2 + 2hxy + by2 = 0, then

m1+ m2 = – 2h/b and m1 m2 = a/b

TS inter 1B pair of straight lines 1

∎ The lines represented by the equation ax2 + 2hxy + by2 = 0 are TS inter 1B pair of straight lines 2

∎ If h2 = ab, then the lines represented by the equation ax2 + 2hxy + by2 = 0 are coincident.

∎ If two lines represented by the equation ax2 + 2hxy + by2 = 0 are equally inclined to the coordinate axes then h = 0 and ab < 0.

∎ The equation of the pair of lines passing through the point (h, k) and

(i) Parallel to the lines represented by the equation ax2 + 2hxy + by2 = 0 is

a (x – h)2 + 2h (x – h) (y – k) + b (y – k)2 = 0

(ii) Perpendicular to the lines represented by the equation ax2 + 2hxy + by2 = 0 is

b (x – h)2 – 2h (x – h) (y – k) + a (y – k)2 = 0

Angle between the lines:

If θ is the angle between the lines represented by the equation ax2 + 2hxy + by2 = 0, then TS inter 1B pair of straight lines 3

∎ If a + b = 0, then two lines are perpendicular.

Area of the triangle:

The area of the triangle formed by the lines ax2 + 2hxy + by2 = 0 and the line lx + my + n = 0 is

TS inter 1B pair of straight lines 4

Angular Bisectors:

⇒ the angle between angular bisectors is always 900
L1 = o, L2 = o are two non-parallel lines the locus of the point P such that the perpendicular distance from P to the first lie is equal to the perpendicular distance from P to second line is called the angular bisector of two lines.

⇒ If two lines are a1x + b1y + c1 = 0 and a2x + b2y + c2 = 0, then the angular bisectors areTS inter 1B pair of straight lines 6

∎ The equation of the pair of angular bisectors of ax2 + 2hxy + by2 = 0 is h (x2 – y2) = (a – b =) xy.

∎ If ax2 + 2hxy + by2 + 2gx 2fy + c= 0 represents a pair of straight lines then

(i) abc + 2fgh – af2 – bg2 – ch2 = 0

(ii) h2 ≥ ab, g2 ≥ ac and f2 ≥ bc

If two lines represented by ax2 + 2hxy + by2 + 2gx 2fy + c= 0 are l1x + m1y + n1 = 0 and l2x + m2y + n2 = 0, then

 ax2 + 2hxy + by2 + 2gx 2fy + c = (l1x + m1y + n1) (l2x + m2y + n2)

a = l1l2; 2h = l1m2 + l2m1; b = m1m2 ; 2g = l1n2 + l2n1;  2f =  m1n2 + m2n1 and c = n1n2  

The point of intersection of the lines represented by ax2 + 2hxy + by2 + 2gx 2fy + c= 0 is TS inter 1B pair of straight lines 7

∎ If two line have same homogeneous path then the lines represented by the first pair is parallel to the lines represented by the second pair.

ax2 + 2hxy + by2 + 2gx 2fy + c= 0 …………… (2)

ax2 + 2hxy + by2 = 0 …………… (1)

TS inter 1B pair of straight lines 8

equation (1) and equation (2) form a parallelogram, one of the diagonals of parallelogram which is not passing through origin is 2gx + 2fy + c = 0.

∎ If two lines represented by ax2 + 2hxy + by2 + 2gx 2fy + c= 0 are parallel then

  • h2 = ab (ii) af2 = bg2 (iii) hf = bg, gh = ab

Distance between parallel lines is TS inter 1B pair of straight lines 9


5. THREE DIMENSIONAL COORDINATES

• Let X’OX, Y’OY be two mutually perpendicular lines passing through a fixed point ‘O’. These two lines determine the XOY – plane (XY- plane). Draw the line Z’OZ perpendicular to XY – plane and passing through ‘O’.

TS inter 1B 3D coordinates 1

The fixed point ‘O’ is called origin and three mutually perpendicular lines X’OX, Y’OY, Z’OZ are called Rectangular coordinate axes.

Three coordinate axes taken two at a time determine three planes namely XOY- plane, YOZ-plane, ZOY-plane or XY-plane, YZ-plane, ZX-plane respectively.

For every point P in space, we can associate an ordered triad (x, y, z) of real numbers formed by its coordinates.

The set of points in space is referred to as ‘Three-Dimensional Space’ or R3– Space.

∗ If P (x, y, z) is a point in a space, then

x is called x-coordinate of P

y is called y-coordinate of P

z is called z-coordinate of P

Distance between two points in space:

∗ Distance between the points A (x1, y1, z1) and B (x2, y2, z2) is TS inter 1B 3D coordinates 2

∗ Distance between the point P (x, y, z) to the origin is TS inter 1B 3D coordinates 3

Translation of axes:

When the origin is shifted to the point (h, k, l), then  

X = x – h; Y = y – k; Z = z – l and x = X + h; y = Y + k; z = Z + l

∗ The foot of the perpendicular from P (x, y, z) to X-axis is A (x, 0, 0).

The perpendicular distance of P from X-axis is TS inter 1B 3D coordinates 4

Similarly,

The perpendicular distance of P from Y-axis is TS inter 1B 3D coordinates 5

The perpendicular distance of P from Z-axis is TS inter 1B 3D coordinates 6

Collinear points: If three or more points lie on the same line are called collinear points.

Section formula:

The point dividing the line segment joining the points A (x1, y1, z1) and B (x2, y2, z2) in the ratio m : n is given by TS inter 1B 3D coordinates 7

The mid-point of the line segment joining the points A (x1, y1, z1) and B (x2, y2, z2) is TS inter 1B 3D coordinates 8

The centroid of the triangle whose vertices are A (x1, y1, z1), B (x2, y2, z2) and C (x3, y3, z3) is TS inter 1B 3D coordinates 8

Tetrahedron:TS inter 1B 3D coordinates 11

→ It has 4 vertices and 6 edges.
→ A Tetrahedron is a closed figure formed by four planes not all passing through the same point.

→ Each edge arises as the line of intersection of two of the four planes.

→ The line segment joining the vertices to the centroid of opposite face. The point of concurrence is        called centroid of Tetrahedron.

→ Centroid divides the line segment in the ratio 3:1.

→ The centroid of the Tetrahedron whose vertices are A (x1, y1, z1), B (x2, y2, z2), C (x3, y3, z3) and C (x4, y4, z4) is TS inter 1B 3D coordinates 10

The line segment joining the points (x1, y1, z1), (x2, y2, z2) is divided by

XY – plane in the ratio – z1: z2

YZ – plane in the ratio – x1: x2

XZ – plane in the ratio – y1: y2


6. DIRECTION COSINES AND RATIOS

Consider a ray OP passing through origin ‘O’ and making angles α, β, γ respectively with the positive direction of X, Y, Z axes.TS inter 1B DC's and DR's 1

Cos α, Cos β, Cos γ are called Direction Cosines (dc’s) of the ray OP.

Dc’s are denoted by (l, m, n), where l = Cos α, m = Cos β, n = Cos γ

• A line in a space has two directions, it has two sets of dc’s, one for each direction. If (l, m, n) is one set of dc’s, then (-l, -m, -n) is the other set.

• Suppose P (x, y, z) is any point in space such that OP = r. If (l, m, n) are dc’s of a ray OP then x = lr, y= mr, z = nr.

• If OP = r and dc’s of OP are (l, m, n) then the coordinates of P are (lr, mr, nr).

• If P (x, y, z) is a point in the space, then dc’s of OP are TS inter 1B DC's and DR's 2

• If (l, m, n) are dc’s of a line then l2 + m2 + n2 = 1.

⇒ cos2α + cos2β + cos2γ = 1.

Direction Ratios:

Any three real numbers which are proportional to the dc’s of a line are called direction ratios (dr’s) of that line.

• Let (a, b, c) be dr’s of a line whose dc’s are (l, m, n). Then (a, b, c) are proportional to (l, m, n) TS inter 1B DC's and DR's 3

  and a2 + b2 + c2 ≠ 1.

• Dr’s of the line joining the points (x1, y1, z1), (x2, y2, z2) are (x2 – x1, y2 – y1, z2 – z1)

• If (a, b, c) are dr’s of a line then its dc’s are TS inter 1B DC's and DR's 4

• If (l1, m1, n1), (l2, m2, n2) are dc’s of two lines and θ is angle between them then Cos θ = l1l2 + m1m2 + n1n2

If two lines perpendicular then l1l2 + m1m2 + n1n2 = 0.

• If (a1, b1, c1), (a2, b2, c2) are dr’s of two lines and θ is the angle between them then

TS inter 1B DC's and DR's 5

If two line are perpendicular then a1a2 + b1b2 + c1c2 = 0.


7. THE PLANE

Plane: A plane is a proper subset of R3 which has at least three non-collinear points and any two points in it.TS inter The Plane 1

∎ Equation of the plane passing through a given point A (x1, y1, z1), and perpendicular to the line whose dr’s (a, b, c) is a(x – x1) + a(y – y1)  + a(z – z1) = 0.

  

∎ The equation of the plane hose dc’s of the normal to the plane (l, m, n) and perpendicular distance from the origin to the pane p is lx + my + nz = p

∎ The equation of the plane passing through three non-collinear points A (x1, y1, z1), B (x2, y2, z2) and C (x3, y3, z3) is

TS inter The Plane 2

∎ The general equation of the plane is ax + by + cz + d = 0, where (a, b, c) are Dr’s of the normal to the plane.

Normal form:

The equation of the plane ax + by + cz + d = 0 in the normal form is

TS inter The Plane 3

Perpendicular distance:

The perpendicular distance from (x1, y1, z1) to the plane ax + by + cz + d = 0 is TS inter The Plane 4

The perpendicular distance from the origin to the plane ax + by + cz + d = 0 isTS inter The Plane 5

Intercepts:TS inter The Plane 8

 X- intercept = aIf a plane cuts X –axis at (a, 0, 0), Y-axis at (0, b, 0) and Z-axis at (0, 0, c) then

Y-intercept = b

Z-intercept = c

The equation of the plane in the intercept form is TS inter The Plane 6                                                                      

The intercepts of the plane ax + by + cz + d =0 is -d/a, -d/b, -d/c

∎ The equation of the plane parallel to ax + by + cz + d = 0 is ax + by + cz + k = 0.

∎ The equation of XY – plane is z = 0.

∎ The equation of YZ – plane is x = 0.

∎ The equation of XZ – plane is y = 0.

∎ Distance between the two parallel planes ax + by + cz + d1 =0 and ax + by + cz + d2 =0 is TS inter The Plane 7

The angle between two planes:

The angle between the normal to two planes is called the angle between the planes.

If θ is the angle between the planes a1 x + b1 y + c1 z + d1 =0 and a2 x + b2 y + c2 z + d2 =0 then

TS inter 1B DC's and DR's 5

If two line are perpendicular then a1a2 + b1b2 + c1c2 = 0.

∎ The distance of the point P (x, y, z) from

TS inter The Plane 9

 


8. LIMITS AND CONTINUITY

Intervals:

Let (a, b) ∈ R such that a ≤ b, then the set

  • {x ∈ R: a ≤ x ≤ b}, is denoted by [a, b] and it is called as closed interval
  • {x ∈ R: a < x < b}, is denoted by (a, b) and it is called as open interval
  • {x ∈ R: a < x ≤ b}, is denoted by (a, b] and it is called as open closed interval
  • {x ∈ R: a ≤ x < b}, is denoted by [a, b) and it is called as closed open interval
  • {x ∈ R: x ≥ a}, is denoted by [a, ∞)  
  • {x ∈ R: x > a}, is denoted by (a, ∞)  
  • {x ∈ R: x ≤ a}, is denoted by (- ∞, a]
  • x ∈ R: x < a}, is denoted by (- ∞, a)

 Neighbourhood:
Let a ∈ R. If δ > 0, then the open interval (a – δ, a + δ) is called the δ – neighbourhood of ‘a’

TS inter Limits and continuity 1

Limit:

If f(x) is a function of x such that if x approaches to a constant value ‘a’, then the value of f(x) also approaches to ‘l’. Then the constant ‘I’ is called a limit of f(x) at x = a

 ⟹ TS inter Limits and continuity 2

Or

A real number l is called the limit of the function f, if for all ϵ> 0 there exist δ > 0 such that TS inter Limits and continuity 3   wheneverTS inter Limits and continuity 4  ⟹ TS inter Limits and continuity 2

Properties of Limits:

TS inter Limits and continuity 5

Sand witch theorem:( Squeez Principle):

f, g, and h are functions such that f(x) ≤ g(x) ≤ h(x), then TS inter Limits and continuity 6 and if TS inter Limits and continuity 7

Left- hand and Right-hand Limits:

If x < a, then  is TS inter Limits and continuity 8called left-hand limit

If x > a, then TS inter Limits and continuity 9 is called right-hand limit

Note:

 TS inter Limits and continuity 10

In Determinate forms:

 if a function f(x) any of the following forms at x = a:

TS inter Limits and continuity 11

Then f(x) is said to be indeterminate at x = a.

TS inter Limits and continuity 12

Continuity:

Condition 1:  If the condition is like x = a and x ≠ a, then we use following property.

If TS inter Limits and continuity 13 then f(x) is continuous at x = a, otherwise f(x) is not continuous.

Condition 2: If the condition is like x ≤ a and x >a, or x < a and x ≥a then we use following property.

If   TS inter Limits and continuity 14  then f(x) is continuous at x = a, otherwise f(x) is not continuous.


9.DIFFERENTIATION

Let f be a function defined on a neighbourhood of a real number ‘a’ if TS inter 1B Differentiation 1exist then we say that f is differentiable at x a and it is denoted by f'(a).

 ∴ f’(a) = TS inter 1B Differentiation 1

∎ If right hand derivative = left hand derivative, then f is differentiable at ‘a’.

  i.e.,  TS inter 1B Differentiation 2

First principle in derivative:

The first principle of the derivative of f at any real number ‘x’ is f’(x) = TS inter 1B Differentiation 3

∎ The differentiation of f(x) is denoted by TS inter 1B Differentiation 4

  TS inter 1B Differentiation 5   means differentiation of ‘y’ with respect to ‘x’

The derivative of constant function is zero i.e., f’(a) = 0 where ‘a’ is any constant.

∎ Let I be an interval in R u and v are real valued functions on I and x ∈ I. Suppose that u and v are differentiable at ‘x’, then

  • (u ± v) is also differentiable at ‘x’ and (u ± v)’(x) = u’ (x) ± v’(x).
  • ‘uv’ is also differentiable at ‘x’ and (uv)’(x) = u(x) v’(x) + v(x) u’(x).
  • αu + βv is also differentiable at ‘x’ and (αu + βv)’(x) = αu’(x) + βv’(x), α, β are constants.
  • is also differentiable at ‘x’ and TS inter 1B Differentiation 7

∎ (f o g)’ (x) = f’(g(x)). g’(x).

TS inter 1B Differentiation 8

Formulae:

TS inter 1B Differentiation 9

Derivative of Trigonometric & Inverse trigonometric functions:

TS-inter-1B-Differentiation-10

Derivative of Hyperbolic & Inverse Hyperbolic functions:

TS inter 1B Differentiation 11

 Parametric Differentiation:

If x = f(t) and y = g(t) then the procedure of finding  in terms of the parameter ‘t’ is called parametric equations. TS inter 1B Differentiation 12

Implicitly differentiation:

An equation involving two or more variables is called an implicit equation.

ax2 + 2hxy + b y2 = 0 is an implicit equation in terms of x and y.

The process of finding TS inter 1B Differentiation 5   from an implicit equation is called implicitly differentiation.

Derivative of one function w.r.t.  another function:

The derivative of f(x) w.r.t g(x) is TS inter 1B Differentiation 13

Second order derivative:

Let y = f(x) be a function, if y is differentiable then the derivative of f is f’(x). If ‘(x) is again differentiable then the derivative of f’(x) is called second order derivative. And it is denoted by f” (x) or TS inter 1B Differentiation 14


 APPLICATION OF DERIVATIVES

10. ERRORS AND APPROXIMATIONS 

Approximations:

Let y f(x) be a function defined an interval I and x ∈ I. If ∆x is any change in x, then ∆y be the corresponding change in y thus ∆y = f (x + ∆x) – f (x).

Let TS-inter-1B-Errors and Approximations1

          ⇒ TS-inter-1B-Errors and Approximations2 - Copy   where ϵ is very small

          ⇒TS-inter-1B-Errors and Approximations3              

          For ‘ϵ.∆x’ is very small and hence, TS-inter-1B-Errors and Approximations4

Approximate value is f (x + ∆x) = f(x) + f’(x). ∆x

Differential:

Let y f(x) be a function defined an interval I and x ∈ I. If ∆x is any change in x, thenTS-inter-1B-Errors and Approximations5 called differential of y = f(x) and it is denoted by df.

                                         ∴ dy = f’(x). ∆x

Errors:

Let y f(x) be a function defined an interval I and x ∈ I. If ∆x is any change in x, then ∆y be the corresponding change in y.

TS-inter-1B-Errors and Approximations 6   


The Following formulae will be used in Solving problems

CIRCLE: TS inter1B application of derivative Circle

If ‘r’ is radius, ‘d’ is diameter ‘P’ is the perimeter or circumference and A is area of the circle then

 d= 2r, P = 2πr = πd and A = πr2sq.u

SECTOR:TS inter1B application of derivative sector

If ‘r’ is the radius, ‘l’ is the length of arc and θ is of the sector then

Area = ½ l r = ½ r2θsq.u.

Perimeter = l + 2r = r (θ + 2) u.

CYLINDER:TS inter1B application of derivative Cylinder

Length of the Arc ‘l’ = rθ (θ must be in radians).

If ‘r is the radius of the base of cylinder and ‘h’ is the height of the cylinder, then

Area of base = πr2 sq.units.

Lateral surface area = 2πrh units.

Total surface area = 2πr (h + r) units.

Volume = πr2 h cubic units.

CONE: TS inter1B application of derivative Cone

If ‘r’ is the radius of base, ‘h’ is the height of cone and ‘l’ is slant height then

l 2 + r2 = h2

Lateral surface area = πrl units.

Total surface area = πr (l + r) sq. units.

Volume = TS inter1B application of derivative geometry 5 cubic units.

SPHERE: TS inter1B application of derivative Sphere

If ‘r’ is the radius of the Sphere then

Surface area = πr2 sq. units.

Volume = TS inter1B application of derivative fraction 7 πr3 cubic units.


11. TANGENTS AND NORMALS

Tangent of a Curve:TS inter1B Tangents & Norma's 1
If the secant line PQ approaches to the same position as Q moves along the curve and approaches to either side then limiting position is called a ‘Tangent line’ to the curve at P. The point P is called point of contact

Let y = f(x) be a curve, P a point on the curve. If Q(≠P) is another point on the curve then the line PD is called secant line.

Gradient of a curve:

 Let y = f(x) be a curve and P (x, y) be a point on the curve. The slope of the tangent to the curve y = f(x) at P is called gradient of the curve.

Slope of the tangent to the curve y = f(x) at P (x, y) is m = TS inter1B Tangents & Normal 2

∎ The equation of the tangent at P (x1, y1) to the curve is y – y1 = m (x – x1) where m =TS inter1B Tangents & Normal 2

Normal of a curve:

Let y = f(x) be a curve and P (x, y) be a point on the curve. The line passing through P and perpendicular to the tangent of the curve y = f(x) at P is called Normal of the curve.

∎ The equation of the tangent at P (x1, y1) to the curve is y – y1 = -1/m (x – x1).
Slope of the normal is -1/m. where m =TS inter1B Tangents & Normal 2

Lengths of tangent, normal, subtangent and subnormal: TS inter1B Tangents & Normals 4

PT → Normal; QN → subnormal
PN → Tangent; QT → subtangent

∎ if m =TS inter1B Tangents & Normal 2  then

TS inter1B Tangents & Normals 5

Angle between two curves:

If two curves intersect at a point P., then the angle between the tangents of the curves at P is called the angle between the curves at P.

∎ If m1, m2 are the slopes of two tangents of the two curves and θ is the angle between the curves then

Tanθ = TS inter1B Tangents & Normals 6

Note:

  • If m1= m2, then two corves are touch each other.
  • if m1× m2 = –1, then two curves intersect orthogonally.

 12. RATE MEASURE

Average rate of change:

if y = f(x) then the average rate of change in y between x = x1 and x = x2 is defined as TS inter1B Rate measure 1

Instantaneous rate of change:

if y = f(x), then the instantaneous rate of change of a unction f at x = x0 is defined as TS inter1B Rate measure 2