#1**0 **

Split green square in half; we have 2 identical rectangles. Rectangle's diagonal is the radius of the semi circle.

Ratio of rectangle's short side to long side is **1 : 2**

The angle between the radius and the longer rectange side is **tan(A) = 1 / 2 = 26.56505118°**

Let the radius **r = 1**

Green square side **a = cos(A) = 0.894427191**

**Green area A _{g} = a² = 0.8 u²**

Blue square diagonal is the radius and it is also **r = 1**

Blue square side **b = sqrt(1/2) = 0.707106781**

**Blue area A _{b} = 2 * b² = 1 u²**

**The ratio of the green area to the blue area is 4 : 5 **

Dragan May 6, 2020