As we can see from the picture, this square consists of four leaves and four irregular figures with equal area. Since you want to learn the square of the area formula πR of a circle, please look at the pictures in the topic carefully. You will find a semicircle with two leaves and a blank area. One side of the square is the diameter. Then take a closer look at the two semicircles. These two semicircles are equal in area and can be regarded as a circle. Then the area of this circle is 6 divided by the square of 2 divided by 3. 14 is 28.26. Then subtract the area of the circle from the area of the square, leaving two irregular graphic areas. 6 times 6 minus 28.26 equals 7.74. (7.74 is the sum of two irregular areas, and there are four such figures in this figure), that is, the sum of all irregular figures is 7.74, multiplied by 2 equals 15.48, and then subtracted from the large square area by four irregular figures, and 36 minus 15.48 equals 20.52.
Then the answer is 20.52 (π takes 3. 14).