You can spell the arc in the lower left corner to the arc on the right, which is just a sector of 1/4, plus a sector of 1/8.

Then the central angle corresponding to the shadow is 3/4π.

Sector? For what? 3/4π divided by 2π multiplied by π multiplied by 1 square? You wrote the answer! !

May I kiss you? Asking for an answer? Search related topics, hoping to draw inferences from one another.