Is it to find the shadow area? The ABC area of the triangle is 50! The area of the semicircle is 1/2*π*5*5= 12.5π! Starting from point D, the AB vertical line intersects with point E! The area of the triangle BDE is 1/2*5*5= 12.5! The sector area is 1/4, and the circle area is 6.25π! So the shadow area is 50+12.5 π-12.5-6.25 π = 37.5+6.25 π.