Area of shaded region = Area of semicircle − Area of △ PQR In right-angle triangle PQR,       ...(Triangle in a semicircle)By pythagorous theorem,QR =242+72​ =25cm∴ Area of semicircle=2π×r2​ =2722​×12.5×12.5​ =245.54cm2Area of △PQR =21​×24×7 =84cm2∴ Area of shaded region = 245.54−84 =161.54cm2