The last question on page 39 of the first volume of the sixth grade mathematics sunshine class is to find the area of the shadow part.
Divide the square into four small squares and then connect the four points. It can be seen that each small shadow part is divided into two equal parts, and the area of each small shadow part is equal to 1 the area of the circle minus the area of the small triangle.
therefore
8x2x2x3. 14÷4-2x2÷2
=25. 12-2
=23. 12 cm2