A white triangle in a blue square. What is it’s top angle α?
Scroll down for a solution to this problem.
Solution
The angle α is 45°.

This solution makes use of the RHS theorem.
Visual solution

Poem
A good spot for surfing
At the sea where it’s so tempting
To surf is not easy
For perfect waves a champion is searching
He dreams from waves and from riding
He glides on the board
As sharp as a sword
It gives good feelings
On the top of the waves
He’s on the top of the world
