The cured surface are of a right circular cylinder is 15π.
If the ratio of the radius to the height is 1:3,
find the hegiht.
thx a lot~
F.2 maths
2009-08-04 7:34 am
回答 (1)
2009-08-04 7:44 am
✔ 最佳答案
The cured surface area = height * 2πr
If the ratio of the radius to the height is 1:3, so r = the height /3 = h/3
15π = h * 2π(h/3)
15= 2h^2 / 3
h^2 = 45/2
h = √22.5 = 4.7434(4 dec.)
2009-08-03 23:55:03 補充：
A right circular cylinder , not a cone.
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