Can somebody please help me with this question?

An isosceles triangle has two equal sides of length 10 cm. Theta is the angle between two equal sides.

a) Express area of a triangle as a function of theta

b) If theta is increasing at a rate of 10 degrees/minute, how fast is area changing at the instant theta=pi/3?

c) at what value of theta will the triangle have the maximum area?

Thanks!!!