Area of the second circle = area of the third circle =3*3*3. 14=28.26.
Remaining area =18 *12-2 * 28.26-113.04 = 46.44.
2. The characters on the prescription can't. . . . In a stupid way, express it directly in words: square length =S S*S=40.
The square of the diameter of a circle =S*S+S*S=80.
The square of the area of a circle = (80 square/2) * 3.14 = 3.14 * 80/4 = 62.8.
3. Square diagonal length = 12.56/3. 14=4 square side length =8 square.
Square area =8
4. Is there a typo? In a semicircle or in a circle? There are a few digits after the decimal point. Besides, it's simple. . .
A. If it is enclosed in a semicircle, the radius of the semicircle =X,
2X*3. 14/2+2X=30.84, so X=6.
Semicircular area =6*6/2*3. 14=56.52.
B. If it is a circle, directly set the formula for calculating the side length of the circle and calculate the diameter, and then you can calculate the area of the circle. Divide directly by 2 to get the area of the semicircle, not counting the head.
5. Before answering this question, was it inside or outside the paparazzi triangle?
If included, the area is the triangle area.
If it is outside, it will be very troublesome, and it will be divided into multiple steps.
The place where dogs can run should be divided into 1 large circle area and 2 small circle areas.
Most of it first:
If the rope length is radius, the calculated circle area is = 452.438+06.
Because it is an equilateral triangle, all three angles are 60 degrees, so you need to subtract the circular area of 1/6 to get the remaining area.
So most of the area =452. 16*5/6=376.8.
Two small circles have the same size, just count one.
Small circle radius = 12-9=3 Small circle area = 3 * 3.14 = 28.26.
The place where dogs can run in the small circle is 65438+ 0/3 of the total area of the small circle.
Therefore, the total area that dogs can reach =376.8+28.26/3+28.26/3=395.64.
I hope it helps you ~ However, I always feel that this should not be a problem in the sixth grade of primary school, right? If it is, it feels like an olympiad ~ ~ ~ hehe.