Pie with square

[Pekis]

Hello,

An old aunt invited 8 of her nephews to come and eat a fruit tart with her. Previously professor of mathematics, she decided to cut the tart in 9 equal but unusual parts:



If you were one of her nephews, could you check if the parts were really equal, computing the values of d (yellow strip's width) and e (orange square's width), in % of the pie radius, before eating it ?

Have fun