Find the area and perimeter of the picture below and tell me what you find.

Let the closed diameter r of a circle.

A

Shadow area = square area-circle area = (2r) 2-pie * r 2 = (4-pie) * r 2

Shadow perimeter = square perimeter+circle perimeter =2R*4 +2R* pie =(4- pie) *(2R)

B

Translate the quarter circle of four corners to its diagonal direction, and the circle obtained is the same as a,

Therefore, the area =(4- pie) * r 2.

At this point, the circumference of the shadow is only the circumference of a circle =2R* pie.

C

After translating the two semicircles to the opposite side, the same figure as A is formed.

Therefore, the area =(4- pie) * r 2.

At this time, perimeter = perimeter+length of the left and right sides of the square =2R* pie +2R*2=2R (pie+2).

From the above calculation, it is found that when the circle is placed in a square in various division forms, the shadow area is not affected, but the shadow perimeter will change.