1, fill in the blanks.
(1) A cuboid has (6) faces. The areas of the (opposite) faces are equal; There are (12) sides, and the (opposite) sides are equal in length.
(2) A cube has (6) faces, and the areas of these (6) faces are all equal; There are (12) sides, and (12) sides are all equal in length.
(3) The lateral area expansion of a cylinder is a rectangle with two (circular) bottoms.
(4) The bottom surface of the cone is round and the side surface is (curved surface).
2. Draw the side development diagram of a cylinder with a height of 2 cm and a bottom radius of 1 cm.
I won't draw this, anyway, the side of the cylinder is a cuboid. Length: 6.28 cm, width: 2 cm.
Draw the real length. 6.28 If you can't draw it, draw 6.3cm..
3. Looking at each of the following geometric figures from above, which figure do you see respectively? Connect with wires.
The first one in the first row is the cylinder connected by the third circle below.
The first one is the second one, and the cube is connected with the fourth one below.
The first one is the third one, and the cone is connected with the second one below. (It is a circle with the center of 1 point)
The first one runs horizontally, and the fourth one is the first connected cuboid below.
The first figure and the third figure in the first line of item 4 can be folded into a cube and put "√" in the brackets below.
Page 75:
Item 1: 1 and 3 are edges, 2 is bottom, and 4 and 5 are front and back. Copy this sentence down. )
It also requires you to mark the height of the fish tank, so you can mark it at the top of the third rectangle: 0.5 cm.
Item 2: Items 2, 3 and 4 can be folded into cubes. Please tick "√" in the brackets below.
Item 3: 1 above is connected with the second one below, and the second one above is connected with 1 below. The third one above is connected with the fourth one below. The fourth one above is connected with the third one below. After the connection, you will see two big forks. )
The fourth item, application questions:
8×7=56 (square centimeter)
7×7=49 (square centimeter)
56 cm2 > 49 cm2
Answer: this cuboid will not leak from a square hole with a side length of 7 cm, because: 56 square cm > 49 square cm.
I'm tired of calling here. -Take a break ~ ~ ~)
Page 76:
1, judge.
The (1) cube has a bottom area of 5 square decimeters and a surface area of 30 square decimeters. (√)
(2) Two cubes with side length of 12cm form a cuboid, and the surface area is reduced by 144cm2. (×)
(3) Cutting a cylinder with a diameter of 4cm along the bottom diameter will increase the surface area by 32cm2. (√)
2. Jia Xiaodong rice cooker is an approximate cylinder. ...
94.2÷3. 14=30 cm
30×30×6=5400 (square centimeter)
A: It takes at least 5400 square centimeters of hard paper to make this packing box.
3. Cylindrical iron drum without cover ...
3. 14×4×5=62.8 (square decimeter)
4÷2=2 (decimeter)
3. 14×2×2= 12.56 (square decimeter)
(12.56+62.8) × 2 =150.72 (square decimeter)
Answer: at least use iron sheet 150.72 square decimeter.
4, roller roller ...
3.14×/kloc-0 /×1.5× 20 = 94.2 (m2)
Answer: It can press 94.2 square meters of road surface every minute.
5. Use 2.4 meters of iron wire ...
2.4÷ 12=0.2 (m)
0.2×0.2×6=0.24 (square meter)
A: ...
Page 77:
1, fill in the blanks.
5600 ml =(5.6) liter 80 cubic decimeter =(0.08) cubic meter.
1.5 liter =( 1500) cubic centimeter 3.05 cubic meter =(3050) cubic decimeter.
2. The triangle below rotates once with AB as the axis. ...
3.14×/kloc-0 /×/kloc-0 /× 3×1/3 = 3.14 (cubic centimeter)
A: ...
3. Rectangular box ...
0.8×0.8× 1.5=0.96 (m3)
A: ...
4. Put a piece of iron with a length of 94.2 cm and a width of 62.8 cm. ...
(1) What is the bottom area of this oil drum?
94.2÷3. 14÷2= 15 (cm)
3.14×15×15 = 706.5 (square centimeter)
A: ...
(2) How many liters of gasoline can an oil drum hold? (Calculated by calculator, the number is kept as an integer)
94.2÷3. 14÷2= 15 (cm)
3.14×15×15× 62.8 = 44368.2 (cubic centimeter)
44368.2 cubic centimeters ≈ 44 liters
A: ...
5. The volume of a cylinder is 100.48 cubic centimeter. ...
Solution: Let the height of this cylinder be x cm.
3. 14×2×2×X= 100.48
X=8
The height of this cylinder is 8 cm.
You can also do this problem:
100.48 ÷ 3.14 ÷ 2 ÷ 2 = 8 (cm)