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Does anyone know the formula for a cones: Volume and Surface Area? Also if you can supply proof for that, it would be very helpful.
Thanks =-)

2007-02-11 02:26:24 · 4 answers · asked by hotmama 2 in Science & Mathematics Mathematics

OK, thanks for the formula for the volume. Now I need the formula for the Surface Area and proof of it. Thanks =-)

2007-02-11 03:13:34 · update #1

4 answers

Let the radius of the base of the cone =r
heiht=h and slant height =l
Then the area of the base of the cone =PI*r^2 sq unitsand the area of the curved surface
=1/2*circumference of the base* slant height
=1/2*2*Pi*r*l sq units=Pi*r*l sq. units
Therefore area of the total surface of a cone
=Pi*r^2+Pi*r*l sq.units or
Pi*r(r+l) sq units
Therefore,we get the formula of total surface area of a cone ,which is Pi*radius(radius+slant height)
Volume of a cone is given by the formula
1/3*area of the base*height
=1/3*Pi*r^2*h

2007-02-11 03:20:42 · answer #1 · answered by alpha 7 · 0 0

V = 1/3 x pi x r cubed. If you think about it it is 1/3 of a cylinder.

SA = pi x r x l ...... ( l is the slant height of the cone.)

2007-02-11 10:30:46 · answer #2 · answered by Anonymous · 0 0

http://www.onlineconversion.com/

2007-02-11 17:31:52 · answer #3 · answered by Cheviot 3 · 0 0

http://www.analyzemath.com/Geometry_calculators/surface_volume_cone.html

2007-02-11 10:33:03 · answer #4 · answered by Del Piero 10 7 · 0 0

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