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

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## Solution

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:

## Video

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

## One reply on “Stars on 45”

A supplement