# Math Help - Another Radions/Arcs/Circles problem

A chord of a circle subtends an angle of theta radians at the centre of the circle. The area of the minor segment cut off by the chord is 1/8 of the area of the circle.

Prove that 4theta= pi + 4 sin theta

Ahhh i have no idea how to do it?

2. Hello juliak
Originally Posted by juliak
A chord of a circle subtends an angle of theta radians at the centre of the circle. The area of the minor segment cut off by the chord is 1/8 of the area of the circle.

Prove that 4theta= pi + 4 sin theta

Ahhh i have no idea how to do it?
If the radius of the circle is $r$, the area of the sector that makes an angle $\theta$ at the centre is $\tfrac12r^2\theta$. The area of the triangle with two sides of length $r$ enclosing an angle of $\theta$ is $\tfrac12r^2\sin\theta$.

So the area of the segment $= ... - ... = \tfrac18\pi r^2$

Fill in the gaps; multiply both sides by $8$, divide by $r$ and you're there.