Question
The area bounded by the curve $x^2+y^2=1$ in first quadrant is
✓
Answer
$(a):$ We have, $x^2+y^2=1$, which is a circle with centre $(0,0)$ and radius $=1$.
Required area
$=\int_0^1 \sqrt{1-x^2} d x$
$=\left[\frac{x}{2} \sqrt{1-x^2}+\frac{1}{2} \sin ^{-1} \frac{x}{1}\right]_0^1$
$=\left[\frac{1}{2} \sin ^{-1} 1\right]=\left(\frac{1}{2} \times \frac{\pi}{2}\right)=\frac{\pi}{4} \text { sq. units }$
Required area
$=\int_0^1 \sqrt{1-x^2} d x$
$=\left[\frac{x}{2} \sqrt{1-x^2}+\frac{1}{2} \sin ^{-1} \frac{x}{1}\right]_0^1$
$=\left[\frac{1}{2} \sin ^{-1} 1\right]=\left(\frac{1}{2} \times \frac{\pi}{2}\right)=\frac{\pi}{4} \text { sq. units }$
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