The area of the smaller region of the circle $x^2 + y^2 = 8$ cut off by the line $x = 2$ is
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → $2(\pi-2)$ sq units
Equation of circle: $x^{2}+y^{2}=8$
Center $(0,0)$, radius $r=\sqrt{8}=2\sqrt{2}$
Line: $x=2$
Perpendicular distance of line from center:
$d=|2-0|=2$
Using formula for area of circular segment:
$A = r^{2}\cos^{-1}\!\left(\frac{d}{r}\right) - d\sqrt{r^{2}-d^{2}}$
Substitute $r=2\sqrt{2}$, $d=2$:
$A = (2\sqrt{2})^{2}\cos^{-1}\!\left(\frac{2}{2\sqrt{2}}\right) - 2\sqrt{(2\sqrt{2})^{2}-2^{2}}$
$A = 8\cos^{-1}\!\left(\frac{1}{\sqrt{2}}\right) - 2\sqrt{8-4}$
$A = 8\left(\frac{\pi}{4}\right) - 2\sqrt{4}$
$A = 2\pi - 4$
Area = $2\pi - 4$ sq. units