(1). How many square meters is this swimming pool?

(20/2) * 3. The square of14 =3 14 square meter.

(2) How many cubic meters does it take to dig this pool?

The square of (20/2) *3. 14*2=628 cubic meters.

(3) After digging, put cement on the bottom and edge of the pool. How many square meters is the plastering area?

(20/2) * 3. The square of14 =3 14 square meter.

20*3. 14*2= 125.6 m2

314+125.6 = 439.6m2.

7. A cylindrical wood with a cross-sectional diameter of 2 decimeters and a length of 5 decimeters, cut the wood in half along the cross-sectional diameter and find the surface area of half.

The square of (2/2) × 3. 14/2 * 2 = 3. 14 square decimeter.

2*3. 14/2*5= 15.7 square decimeter.

3.14+15.7 =18.84 square decimeter.

8. Dig a cylinder with a bottom radius of 1 cm and a height of 1 cm from the center of the upper, lower, front, rear and left sides of a cubic steel block with a length of 4, and calculate the surface area of the dug steel block.

4*4*4=64 square centimeters

1* 2 * 3.14 *1* 6 = 37.68 square centimeters.

64+37.68= 10 1.68 cm2

9.( 1). How deep is the oil in the barrel?

169.56/3 /3. 14/2 squared =3 decimeters.

2. If the area is required, it is: 3 *3. 14 squared =28.26 square decimeter.

3.78.5*(50/5*4)=3 140 cubic centimeter.

Fill in the blanks.

The length is (25. 12), the width is (5), and the area is (125.6) cm2.

2. The cross-sectional diameter is (3) cm and the area is (7.065) cm.

3. The sum of the areas of the two bottom surfaces is (3 14) square centimeters.