It depends on the conditions. (1) window area = length× width = (half b+ half b+b)×a=2ab.

(2) As shown in the figure, the curtain is divided into three parts. The internal angles of the first part and the third part (from left to right) are 90 degrees each, and the internal angle of the second part (the largest one in the middle) is 180 degrees. 90+90+ 180 = 360 is a circle with a radius of half B.

So (2)=s circle =π r square = quarter π b square.

(3) According to (1) and (2), the sunlight exposure area is window area-curtain area =2ab- 4 π b square,

Don't ask questions