Respuesta :

sqdancefan
The area of the circle is 
 Area = π·r² = π·(10 cm)² = 100π cm²

The area of the regular pentagon is
 Area = (5/2)sin(72°)·(10 cm)² = 250·sin(72°) cm²

The shaded area is the difference of these:
 (100π -250sin(72°)) cm² ≈ 76.4 cm²