The radius of a sphere is 3 cm. The radius of the base of a cone is also 3 cm.

The volume of the sphere is 3 times the volume of the cone.

Work out the curved surface area of the cone, giving your answer as a multiple ofpi.

Thanks.

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- March 8th 2009, 09:19 AMGAdamssphere cone problem
The radius of a sphere is 3 cm. The radius of the base of a cone is also 3 cm.

The volume of the sphere is 3 times the volume of the cone.

Work out the curved surface area of the cone, giving your answer as a multiple of*pi*.

Thanks. - March 8th 2009, 09:51 AMGrandadVolume of sphere and come
- March 8th 2009, 11:13 AMearboth
Let s denote the slanted height, r the radius of the base circle and h the height of the cone. Then the curved surface of a cone is a sector of a circle with radius s. The area of the curved surface, the area of the complete circle, the circumference of the base circle = arc of the sector and the circumference of the complete circle are directly proportional:

- March 8th 2009, 11:17 AMGAdams
- March 8th 2009, 11:25 AMGrandadSurface area of cone
Hello GAdams

earboth has given you the formula for the curved surface area of a cone. You now need to work out the value of , which you can do using Pythagoras' Theorem. (It's the easiest right-angled triangle of all!)

Then plug the values of and into this formula, and you're there.

Grandad - March 9th 2009, 12:37 PMGAdams
- March 9th 2009, 12:44 PMearboth
- March 9th 2009, 01:09 PMGAdams
- March 14th 2009, 04:48 AMosmosis786Dont understand
- March 14th 2009, 05:58 AMGrandadSphere and cone
- March 14th 2009, 08:11 AMosmosis786Your absolutely correct
i never read the question properly haha(Speechless)