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Provide solution for RD Sharma Maths Class 12 Chapter 20 Areas of Bounded Region Exercise 20.3 question 17.

Answers (1)

Answer: \frac{\pi}{3}

Hint:

use basic concepts.

Given: The equations of the curves are

x^2+y^2=4

x=\sqrt{3}y

Solution: Obviously x^2+y^2=4  is a circle having centre at (0, 0) and radius 2 units. Forgraph of line

x=\sqrt{3}y.

x 0 1
y 0 0.58

 

For intersecting point of given circle and line

Putting  x=\sqrt{3}  in x^2+y^2=4  we get

\begin{aligned} &(\sqrt{3} y)^{2}+y^{2}=4 \\ &3 y^{2}+y^{2}=4 \\ &4 y^{2}=4 \\ &y=\pm 1 \\ &x=\pm \sqrt{3} \end{aligned}

Intersecting points are (\sqrt{3},1 ), (-\sqrt{3},-1)

Shaded region is required region.

 

Now required area =\int_{0}^{\sqrt{3}} \frac{x}{\sqrt{3}} d x+\int_{0}^{\sqrt{3}} \sqrt{4-x^{2}}

\begin{aligned} &=\frac{1}{\sqrt{3}}\left[\frac{x^{2}}{2}\right]_{0}^{\sqrt{3}}+\left[\frac{x \sqrt{4-x^{2}}}{2}+\frac{4}{2} \sin -\frac{x}{2}\right]_{\sqrt{3}}^{2} \\ &=\frac{1}{2 \sqrt{3}}(3-0)+\left[2 \sin -{ }^{1}-\left(\frac{\sqrt{3}}{2}+2 \sin -{ }^{1} \frac{\sqrt{3}}{2}\right)\right] \end{aligned}

\begin{aligned} &=\frac{\sqrt{3}}{2}+\left[2 \frac{\pi}{2}-\frac{\sqrt{3}}{2}-\frac{2 \pi}{3}\right] \\ &=\frac{\sqrt{3}}{2}+\pi-\frac{\sqrt{3}}{2}-\frac{2 \pi}{3} \\ &=\pi-\frac{2 \pi}{3} \\ &=\frac{\pi}{3}(\text { proved }) \end{aligned}

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