Question

一块直径为a+b的圆形木板,从中挖去直径分别为a与b的两个圆,则剩下木板的面积是

Answer 1

=[0.5(a+b)]^2*π-(0.5a)^2*π-（0.5b）^2π

[(=a+b)^2-a^2-b^2]*1/4*π

=0.5abπ