$ABC$ is a triangle with $\angle A=30°$, $BC=10cm$. The area of the circum circle in the triangle is:

Question

$ABC$ is a triangle with $\angle A=30°$, $BC=10cm$. The area of the circum circle in the triangle is:

$a$. $100\pi$ sq.cm

$b$. $5$ sq. cm

$c$. $25$ sq. cm

$d$. $\dfrac {100\pi}{3}$ sq. cm

I tried to use the formula for the area of triangle that:

$$A=\dfrac {1}{2} a.b.\sin C$$

But didn't work?

Answer 1

Hint

If $r$ is the circumradius, then

$$\frac{BC}{\sin A}=2r$$

https://en.m.wikipedia.org/wiki/Law_of_sines