There are many ways to create the solution as it is something like a jigsaw. We used this method

1. Mark the right angles (use the fact the a radius and tangent at a point are at right angles)

2. Make all occurrences of the angle a

3. Mark the unit length

The diagram then becomes

To work out all of the areas we need to decide what unit of measurement the angle $a$ is in. Of course, we choose radians: there are $2\pi$ radians in a circle. We will also need to know the formula for the area of a circle and the area of a triangle. In this case, the areas are given as

The two largest areas are equal for around 0.40523 radians (23.2 degrees).