The lunes of Alhazen. The two blue lunes together have the same area as the green right

triangle. See the GeoGebra proof etc here: 

The duty of the man who investigates the writings of scientists, if learning the truth is his goal, is to make himself an enemy of all that he reads, and ... attack it from every side. He should also suspect himself as he performs his critical examination of it, so that he may avoid falling into either prejudice or leniency.

— Alhazen


More from the series Cosmos: A Spacetime Oddesy – episode 5 “Hiding in the Light”



Mark de LA says
Maybe this works as an embed: