Question

如图,从一块直径为a+b的圆形钢板上,截去直径分别为a和b的两个圆.求剩余钢板的面积

Answer 1

∏(a/2+b/2)^2-∏(a/2)^2-∏(b/2)^2

=∏(a/2)^2+∏(b/2)^2+1/2*a*b∏-∏(a/2)^2-∏(b/2)^2

=1/2*ab∏