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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).
Geometric Trig
Age 16 to 18
ShortChallenge Level 
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).
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