A chord $10 \mathrm{~cm}$ long is drawn in a circle whose radius is $5 \sqrt{2} \mathrm{~cm}$. Find area of both the segments.
We know that the area of minor segment of angle θ in a circle of radius r is,
$A=\left\{\frac{\pi \theta}{360^{\circ}}-\sin \frac{\theta}{2} \cos \frac{\theta}{2}\right\} r^{2}$
It is given that the chord AB divides the circle in two segments.
We have $O A=5 \sqrt{2} \mathrm{~cm}$ and $A B=10 \mathrm{~cm}$. So,
$A L=\frac{A B}{2} \mathrm{~cm}$
$=\frac{10}{2} \mathrm{~cm}$
$=5 \mathrm{~cm}$
Let $\angle A O B=2 \theta$. Then,
$\angle A O L=\angle B O L$
$=\theta$
$\ln \Delta O L A$, we have
$\sin \theta=\frac{A L}{O A}$
$=\frac{5}{5 \sqrt{2}}$
$=\frac{1}{\sqrt{2}}$
$\theta=\sin ^{-1} \frac{1}{\sqrt{2}}$
$=\frac{1}{\sqrt{2}}$
$\theta=\sin ^{-1} \frac{1}{\sqrt{2}}$
$=45^{\circ}$
Hence, $\angle A O B=90^{\circ}$
Now using the value of $r$ and $\theta$, we will find the area of minor segment
$A=\left\{\frac{90^{\circ} \pi}{360^{\circ}}-\sin \frac{90^{\circ}}{2} \cos \frac{90^{\circ}}{2}\right\} \times 5 \sqrt{2} \times 5 \sqrt{2}$
$=\left\{\frac{\pi}{4}-\sin 45^{\circ} \cos 45^{\circ}\right\} \times 50$
$=\frac{3.14 \times 50}{4}-\frac{1}{\sqrt{2}} \times \frac{1}{\sqrt{2}} \times 50$
$=39.25-25$
$A=14.25 \mathrm{~cm}^{2}$
Area of circle $=\pi r^{2}$
$=3.14 \times 5 \sqrt{2} \times 5 \sqrt{2}$
$=157.15 \mathrm{~cm}^{2}$
Area of major segment = Area of circle-Area of minor segment
$=157-14.25$
$=142.75 \mathrm{~cm}^{2}$