We have an isosceles triangle inscribed in a circle (that is, all its vertices lie on the circumference of the circle).
The vertex angle of the triangle — the angle between the two equal sides — is \theta.
The circle has radius R=1.
Express the area of the triangle as a function of \theta.
(Hint: You may use the formula for the area of a triangle inscribed in a circle: \tfrac{abc}{4R}, where a, b, c are the side lengths. But this formula is not mandatory. The result should simplify to the form \sin\theta(1+\cos\theta)