9514 1404 393
Answer:
shaded/square = (50π cm²)/(400 cm²) = π/8
Explanation:
The quarter circle has area ...
A = (1/4)(πr²) = π/4(20 cm)² = 100π cm²
The half-circle has area ...
A = (1/2)(πr²) = π/2(10 cm)² = 50π cm²
Then the area of the shaded portion is ...
shaded = 100π cm² -50π cm² = 50π cm²
__
The area of the square is ...
A = s² = (20 cm)² = 400 cm²
Then the ratio of interest is ...
shaded/square = (50π cm²)/(400 cm²) = π/8