# NCERT solution class 12 chapter 2 Application of Integrals exercise 2.1 mathematics part 2

## EXERCISE 2.1

#### Question 1:

Find the area of the region bounded by the curve y2 = x and the lines x = 1, x = 4 and the x-axis. The area of the region bounded by the curve, y2 = x, the lines, x = 1 and x = 4, and the x-axis is the area ABCD. #### Question 2:

Find the area of the region bounded by y2 = 9x, x = 2, x = 4 and the x-axis in the first quadrant. The area of the region bounded by the curve, y2 = 9xx = 2, and x = 4, and the x-axis is the area ABCD. #### Question 3:

Find the area of the region bounded by x2 = 4yy = 2, y = 4 and the y-axis in the first quadrant. The area of the region bounded by the curve, x2 = 4yy = 2, and y = 4, and the y-axis is the area ABCD. #### Question 4:

Find the area of the region bounded by the ellipse The given equation of the ellipse, , can be represented as It can be observed that the ellipse is symmetrical about x-axis and y-axis.

∴ Area bounded by ellipse = 4 × Area of OAB Therefore, area bounded by the ellipse = 4 × 3π = 12π units

#### Question 5:

Find the area of the region bounded by the ellipse The given equation of the ellipse can be represented as  It can be observed that the ellipse is symmetrical about x-axis and y-axis.

∴ Area bounded by ellipse = 4 × Area OAB Therefore, area bounded by the ellipse = #### Question 6:

Find the area of the region in the first quadrant enclosed by x-axis, line and the circle The area of the region bounded by the circle, , and the x-axis is the area OAB. The point of intersection of the line and the circle in the first quadrant is .

Area OAB = Area ΔOCA + Area ACB

Area of OAC Area of ABC  Therefore, required area enclosed =

32 + π3 – 32 = π3 square units

#### Question 7:

Find the area of the smaller part of the circle x2 + y2 = a2 cut off by the line The area of the smaller part of the circle, x2 + y2 = a2, cut off by the line, , is the area ABCDA. It can be observed that the area ABCD is symmetrical about x-axis.

∴ Area ABCD = 2 × Area ABC  Therefore, the area of smaller part of the circle, x2 + y2 = a2, cut off by the line, , is units.

#### Question 8:

The area between x = y2 and x = 4 is divided into two equal parts by the line x = a, find the value of a.

The line, x = a, divides the area bounded by the parabola and x = 4 into two equal parts.

âˆ´ Area OAD = Area ABCD It can be observed that the given area is symmetrical about x-axis.

â‡’ Area OED = Area EFCD From (1) and (2), we obtain Therefore, the value of a is .

#### Question 9:

Find the area of the region bounded by the parabola x2 and The area bounded by the parabola, x2 = y,and the line, , can be represented as The given area is symmetrical about y-axis.

âˆ´ Area OACO = Area ODBO

The point of intersection of parabola, x2 = y, and line, x, is A (1, 1).

Area of OACO = Area Î”OAM â€“ Area OMACO

Area of Î”OAM  Area of OMACO â‡’ Area of OACO = Area of Î”OAM â€“ Area of OMACO Therefore, required area = units

#### Question 10:

Find the area bounded by the curve x2 = 4y and the line x = 4– 2

The area bounded by the curve, x2 = 4y, and line, x = 4– 2, is represented by the shaded area OBAO. Let A and B be the points of intersection of the line and parabola.

Coordinates of point .

Coordinates of point B are (2, 1).

We draw AL and BM perpendicular to x-axis.

It can be observed that,

Area OBAO = Area OBCO + Area OACO … (1)

Then, Area OBCO = Area OMBC – Area OMBO Similarly, Area OACO = Area OLAC – Area OLAO Therefore, required area = #### Question 11:

Find the area of the region bounded by the curve y2 = 4x and the line x = 3

The region bounded by the parabola, y2 = 4x, and the line, x = 3, is the area OACO. The area OACO is symmetrical about x-axis.

∴ Area of OACO = 2 (Area of OAB) Therefore, the required area is units.

#### Question 12:

Area lying in the first quadrant and bounded by the circle x2 + y2 = 4 and the lines x = 0 and = 2 is

A. π

B. C. D. The area bounded by the circle and the lines, x = 0 and x = 2, in the first quadrant is represented as  Thus, the correct answer is A.

#### Question 13:

Area of the region bounded by the curve y2 = 4xy-axis and the line y = 3 is

A. 2

B. C. D. The area bounded by the curve, y2 = 4xy-axis, and y = 3 is represented as  Thus, the correct answer is B.

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