ncert cbse mathematics class 12th differential equations
exercise 9.4 variable separable differential equations type
solve dy/dx = [1-cosx]/[1+cosx]
here this is of the type variable separable
so
dy/dx = [1-cosx]/[1+cosx]
dy = { [1-cosx]/[1+cosx] }dx
using trigonometric formula
1-cosx =2 [ sin(x/2)] ^2
1+cosx =2 [ cos(x/2)] ^2
dy = { [{2 [ sin(x/2)] ^2} ] / {2 [ sin(x/2)] ^2} }dx
dy =[tan(x/2)] ^2 dx
we again have to use trigonometric formula to change the
[tan(x/2)] ^2 in terms of [sec(x/2)] ^2 -1 before integrating
dy ={[sec(x/2)] ^2 -1 }dx
now integrating on both sides using integration formula
y = { [tan(x/2)] /[1/2] } -x + C
do not forget to divide by the coefficient of x while integrating
y=2 [tan(x/2)] - x +C
you can use the following for more explanation
2. solve (dy/dx) = sqrt[4-(y^2)]
separating the variables
dy/{sqrt[4-(y^2)]} =dx
now integrating on both sides using integration formula
and noting that 4=(2^2) so that a=2
we get
arc[sin(y/2)]=x+C
y/2 =sin(x+C)
y=2 sin(x+C)
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ncert cbse 12th mathematics
exercise 9.4
differential equations
variable separable type of differential equations
solve dy/dx = [1-cosx]/[1+cosx]
solution
2. solve (dy/dx) = sqrt[4-(y^2)]
solution
ncert cbse 10th mathematics
co ordinate geometry chapter 7
exercise 7.4 optional exercise
Determine the ratio in which the line 2x + y – 4 = 0 divides the line segment joining the points A(2, – 2) and B(3, 7).
solution
2. Find a relation between x and y if the points (x, y), (1, 2) and (7, 0) are collinear.
solution
3. Find the centre of a circle passing through the points (6, – 6), (3, – 7) and (3, 3).
solution
4. The two opposite vertices of a square are (–1, 2) and (3, 2). Find the coordinates of the other two vertices.
solution
6. The vertices of a ∆ ABC are A(4, 6), B(1, 5) and C(7, 2). A line is
drawn to intersect sides AB and AC at D and E respectively so that
[AD/AB] =[AE/AC] =[1/4] Calculate the area of ∆ ADE and compare it with
the area of ∆ ABC
solution
7. Let A (4, 2), B(6, 5) and C(1, 4) be the vertices of ∆ ABC.
(i) The median from A meets BC at D. Find the coordinates of the point D.
(ii) Find the coordinates of the point P on AD such that AP : PD = 2 : 1
solution
8. ABCD is a rectangle formed by the points A(–1, –1), B(– 1, 4), C(5, 4) and
D(5,
– 1). P, Q, and S are the mid-points of AB, BC, CD and DA respectively.
Is the quadrilateral PQRS a square? a rectangle? or a rhombus? Justify
your answer.
solution
exercise 7.3
Find the area of the triangle whose vertices are
(2, 3), (–1, 0), (2, – 4)
solution
(ii) (–5, –1), (3, –5), (5, 2)
solution
2. In each of the following find the value of ‘k’, for which the points are collinear.
(7, –2), (5, 1), (3, k)
solution
(ii) (8, 1), (k, – 4), (2, –5)
solution
4. Find the area of the quadrilateral whose vertices, taken in order, are (– 4, – 2), (– 3, – 5), (3, – 2) and (2, 3).
solution
exercise 7.2
10.Find the area of a rhombus if its vertices are (3, 0), (4, 5), (– 1, 4) and (– 2, – 1) taken in order
solution
9. Find the coordinates of the points which divide the line segment joining
A(– 2, 2) and B(2, 8) into four equal parts.
solution
8. If A and B are (– 2, – 2) and (2, – 4), respectively, find the
coordinates of P such that AP =(3/7) AB and P lies on the line segment
AB.
solution
7. Find the coordinates of a point A, where AB is the diameter of a circle whose centre is (2,-3) and B is (1,4)
solution
5. Find the ratio in which the
line segment joining A(1, – 5) and B(– 4, 5) is divided by the x-axis.
Also find the coordinates of the point of division.
solution
4.Find the ratio in which the line segment joining the points (– 3, 10) and (6, – 8) is divided by (– 1, 6).
solution
2. Find the coordinates of the points of trisection of the line segment joining
(4, –1) and (-2,-3)
solution
Find the coordinates of the point which divides the join of (–1, 7) and (4, –3) in the
ratio 2 : 3
solution
exercise 7.1
Find the distance between the following pairs of points :(2, 3), (4, 1)
solution
(ii) (– 5, 7), (– 1, 3)
solution
(iii) (a, b), (– a, – b)
solution
2. Find the distance between the points (0, 0) and (36, 15).
solution
3. Determine if the points (1, 5), (2, 3) and (– 2, – 11) are collinear.
solution
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