As can be seen from the figure, the area of area 1 = 2 times of area 2; Area of area 2 = small square minus the area of a quarter circle; Area of area 3 = area of right triangle minus area of isosceles triangle minus area of sector.
2. Solution process:
Step 1: Calculate the sum of the areas of s 1 and s2:
In the second step, the nature of the central angle and the central angle is b = 2a, and it is known at the same time.
Available? ,
Understand? ,
In the third step, the distance from the left end of Zone 3 to the central horizontal line is 4.
Therefore, the area of area 3 is:
The fourth step, to sum up, the area of the shadow part is: