Stars on 45

A square containing a rectangle. What is the red fraction?

Scroll down for a solution to this problem.


The red fraction is 1/2.

Making use of Stéphane Bernard‘s circle – match up regions and use Pythagoras on the triangle with dashed hypotenuse to show that A = B+C:

Solution by Matthew Arcus.


Please find here the video solution: Video: Stars on 45.

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