Okay, I have a question on an exam paper that I just can't seem to do.

Well okay. It's a circle. It's been cut. So we have a triangle and a sector.

The radius is 4cm. The sector area is Acm^2 and the perimeter is Xcm and X = 3A.

Now. I have to show with that information that the angle is 0.4radians.

I can't figure it out.

I need to figure out the perimeter. Then I can just sub it into 1/2*R^2*the angle in radians and then BAM I should have showed it.