1, the width of a large rectangle is equal to the sum of the widths of two small rectangles, and the area of a large rectangle is equal to half the area of a square (1/2).

2. The big rectangle is divided into two trapezoids B and a blank part, and the area of B accounts for 5/24 of the square area.

Then the blank trapezoid accounts for 1/2-5/24 = 7/24 of the square area.

3. The area of A is square1/2-118-7/24 =11/72.

The area of a square is 5. 5 ÷ 1 1/72 = 36 (square centimeter)

5。 B Shadow area 36 x 5/24 = 7. 5 (square centimeter)