As shown in the figure, the rectangle ABCD rotates 90 ° clockwise around point a to the position of rectangle ab1c1d1. Ad = 10, calculate the area swept by edge BC

As shown in the figure, the rectangle ABCD rotates 90 ° clockwise around point a to the position of rectangle ab1c1d1. Ad = 10, calculate the area swept by edge BC

It's much simpler than the right triangle
Let the side length of rectangle AB be a and the diagonal length be B, then 10 ^ 2 + A ^ 2 = B ^ 2
Area = ABCC1 area triangle ac1b1 sector abb1
=(πb^2/4+10a/2)-10a/2-πa^2/4
=π(b^2-a^2)/4
=25π