

NCERT Solutions for Class 12 Maths Chapter 8 Miscellaneous Exercise
Solve The Following Questions NCERT Solutions for Class 12 Maths Chapter 8 Exercise 8.2:
Question 1. Find the area of the circle 4 x 2 + 4 y 2 = 9 which is interior to the parabola x 2 = 4 y Solution : The required area is represented by the shaded area OBCDO.
Solving the given equation of circle, 4
x
2
+ 4
y
2
= 9, and parabola,
x
2
= 4
y
, we obtain the point of intersection as B(√2,1/2) and D (-√2,1/2).
It can be observed that the required area is symmetrical about
y
-axis.
∴ Area OBCDO = 2 × Area OBCO
We draw BM perpendicular to OA.
Therefore, the coordinates of M are (√2,0).
Therefore, Area OBCO = Area OMBCO – Area OMBO
Therefore, the required area OBCDO is
NCERT Solutions for Class 12 Maths Chapter 8 Exercise 8.1
Question 2. Find the area bounded by curves ( x – 1) 2 + y 2 = 1 and x 2 + y 2 = 1 Solution : The area bounded by the curves, ( x – 1) 2 + y 2 = 1 and x 2 + y 2 = 1, is represented by the shaded area as
On solving the equations, (
x
– 1)
2
+
y
2
= 1 and
x
2
+
y
2
= 1, we obtain the point of intersection as A (1/2,√3/2) and B (1/2,√3/2) .
It can be observed that the required area is symmetrical about
x
-axis.
∴ Area OBCAO = 2 × Area OCAO
We join AB, which intersects OC at M, such that AM is perpendicular to OC.
The coordinates of M are (1/2,0).
Therefore, required area OBCAO =
units.
Question 3. Find the area of the region bounded by the curves
y
=
x
2
+ 2,
y
=
x
,
x
= 0 and
x
= 3
Solution :
The area bounded by the curves,
y
=
x
2
+ 2,
y
=
x
,
x
= 0, and
x
= 3, is represented by the shaded area OCBAO as
Then, Area OCBAO = Area ODBAO – Area ODCO
Question 4. Using integration, find the area of the region bounded by the triangle whose vertices are (–1, 0), (1, 3) and (3, 2).
Solution :
BL and CM are drawn perpendicular to
x
-axis.
It can be observed in the following figure that,
Area (ΔACB) = Area (ALBA) + Area (BLMCB) – Area (AMCA) … (1)
Therefore, from equation (1), we obtain
Area (ΔABC) = (3 + 5 – 4) = 4 units.
5. Using integration, find the area of the triangular region whose sides have the equations
y
= 2
x
+1,
y
= 3
x
+ 1 and
x
= 4.
Solution :
The equations of sides of the triangle are
y
= 2
x
+1,
y
= 3
x
+ 1, and
x
= 4.
On solving these equations, we obtain the vertices of triangle as A(0, 1), B(4, 13), and C (4, 9).
It can be observed that,
Area (ΔACB) = Area (OLBAO) –Area (OLCAO)
Question 6. Choose the correct answer:
Smaller area enclosed by the circle
x
2
+
y
2
= 4 and the line
x
+
y
= 2 is
(A)2 (π – 2)
(B). π – 2
(C). 2π – 1
(D). 2 (π + 2)
Solution : The smaller area enclosed by the circle, x 2 + y 2 = 4, and the line, x + y = 2, is represented by the shaded area ACBA as
It can be observed that,
Area ACBA = Area OACBO – Area (ΔOAB)
Therefore, option (B) is correct.
Question 7. Choose the correct answer:
Area lying between the curves
y
2
= 4
x
and
y
= 2
x
is
(A) 2/3
(B) 1/3
(C) 1/4
(D) 3/4
Solution :
The area lying between the curve,
y
2
= 4
x
and
y
= 2
x
, is represented by the shaded area OBAO as
The points of intersection of these curves are O (0, 0) and A (1, 2).
We draw AC perpendicular to
x
-axis such that the coordinates of C are (1, 0).
∴ Area OBAO = Area (OCABO) – Area (ΔOCA)
Therefore, option (B) is correct.
