The surface area of a cone is...?

Question

The surface area of a cone is 24πcm^2 (twenty four pi centimeters squared) and the lateral area is 15πcm^2 (fifteen pi centimeters squared). What is the slant height and the height of this cone?

The formula for finding the lateral area of a cone is π * radius * slant and the formula for finding the surface area is lateral area * area of the base.

I have the answer, but I have no clue how to do it: I got 15/9 as the slant, which is wrong. Help, please!

15/9 can't be right, because then how would you get the height?

Answer 1

The surface area of a cone is...... eaten after all the ice cream is gone.

Answer 2

Under the Icecream or it will fall on the ground.

Total Surface Area = 75.39816 cm^2
Total Lateral Area = 47.12385 cm^2
Surface - Lateral = 28.27431 cm^2 = area of the base

28.27431 / Pi (3.14159) = 9 = r^2 r=3

Lateral Formula = 47.12385 = (3.14159)3(s)
= 47.12385 = 9.42477*s
47.12385/9.42477=s
47.12385/9.42477=5 s=5 = slant height

s=sqrt[r^2+h^2]

5=sqrt[3^2+h^2]
5=sqrt 25
25-3^2 = 16
thus h^2 = 16 h=4 = height

Check r^2+h^2=s^2
9+16=25
Proof

I think this is right. Been awhile since I've done this.

Handy little website you might want to use to find formulas

http://mathforum.org/dr.math/faq/formulas/faq.cone.html


Good luck

Answer 3

i got 15/9 too...