Hello

I have a question where I need to find the area of a circle inscribed, I think that's the right word, in a sector. The circle touches both straight edges of the sector and the arc. I know the angle of the sector, $\displaystyle \dfrac{\pi}{3}$ and the lengths of the two straight edges, 6 cm. I figure I need to find the radius of the circle.

I'm just after a hint. Thank you.