The surface area of a cone is 122.4 in2 and the slant height is 10 in. What is the radius of the cone?

Question

apoorvk · Answer

I suppose that area is the lateral area?

anyways, are of a cone = pi * radius(r) * slant height(l)

can you use this?

additionally if that's the total surface area (that is lateral area plus the base area), then are = pi * r * l    +   pi * r^2

anonymous · Answer

^^ its surface area

anonymous · Answer

The surface area of a cone is 122.4 in2 and the slant height is 10 in. What is the radius of the cone?

 
 A. 3 in. 
 
 B. 5 in. 
 
 C. 6.12 in. 
 
 D. 9 in.

anonymous · Answer

we dont know radius, B/c we need to find the radius

anonymous · Answer

man use the formula that apoorvk has given and mold it for radius

anonymous · Answer

how i tried

apoorvk · Answer

Just plug in the values! you have l=10 inches given. pi = 3.14. Now plug it in the formula, calculate and enjoy!