1. If the volume and height of the cylinder and the cone are equal, then the bottom area of the cylinder is (b) of the bottom area of the cone.

A.3 times B. 1/3 C.6 times D.9 times

2. A cylindrical wood with a ground radius of 3dm and a height of 10dm. After sawing the wood into two equal parts along the bottom diameter, the surface area increased by (c) square decimeter.

A.28.26 B.56.52 C.60 D. 120

fill-in-the-blank question

1/5 of 1.A is equal to 1/6 of B, and the ratio of B to A is _ 5: 6 _ _.

application problem

1. Tapered wheat pile, with a bottom circumference of 6.28m and a height of 3m. If wheat weighs 750 kilograms per cubic meter, how many kilograms is this pile of wheat?

Solution: radius r= perimeter ÷ 2π = 6.28 ÷ 6.28 =1m.

Wheat weight = π r2h/3× 750 = 3.14×1×1× 3 ÷ 3× 750 = 2355kg.

2. The transverse area of the cylinder is 1 88.4cm2 and the height is1decimeter. Find the volume of this cylinder.

Solution: Bottom perimeter =188.4÷10 =18.84 cm.

Radius = perimeter ÷ 2π = 18.84 ÷ 6.28 = 3cm.

Therefore, the bottom area s = π r 2 = 3. 14× 3× 3 = 28.26 cm2.

The volume V=Sh=28.26× 10=282.6 cubic centimeters.

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