Hello, muks!

Let intersect at1. is a point on side of a square

From point , a perpendicular is drawn to , cutting at

Prove: .

Code:Q D * - - - - * - - - - * C | * | | * | | * | | * | | * *P | R* β| | * * | | * *α| | * α β *| A * - - - - - - - - - * B

In right triangle , let

Then , the complement of

Hence, , the complement of

Right triangles have: .

Therefore: .