S3 Area and Volume

小芝芝

2011-04-01 5:46 am

Please solve the following questions.

1. The base circumference of a right circular cone is 20(3.1415)m and its
height is 8m. Find the volume of the cone.

2. The diameter of a right circular cone is 3m and the slant height is 2.5cm.
Find the volume of the cone.

3. A cone of ice-cream has base diameter 7cm and slant height 12.5cm.
Find its volume.

4. Find the height of the circular cone if its volume is 40cm^3 and base
area is 20cm^2.

5. Find the base radius of the circular cone given that its volume
is 243(3.1415)cm^3 and its height is 9 cm.

回答 (1)

ShikaP

2011-04-01 6:50 am

✔ 最佳答案

1. when pi=3.1415
the base ratio=10m
volume=1/3*pi*10^2*8
=837.73
=838m^3,cor to 3 sig fig
2.radius=1.5m
so volume=1/3*pi*1.5^2*2.5=5.8904=5.89m^3,cor to 3 sig fig
3.radius=3.5cm
height=sqrt (12.5^2-3.5^2) =12
volume=1/3*pi*3.5^2*12=153.93=154cm^2,cor to 3 sig fig
4.let the height is x cm,
1/3*20*x=40
20x=120
x=6
so the height is 6cm
5.from (1),pi=3.1415
let the radius is r cm
243pi=1/3*pi*r^2*9
243=3r^2
r^2=81
r=9
the base radius is 9cm

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