find the surface area of the right cone?

Question

13cm height
6.5 radius

Answer 1

Do this the easy way. Assuming that the radius is really 13cm, not 6.5cm, the distance from the apex to the circumference is 13√2, and the circumference at the base is 26π. The area is just (1/2)(13√2)(26π), or (169π√2). To understand why, draw a lot of skinny triangles from the circumference to the apex.

By the way, for a RIGHT cone, the radius should have been 13cm, not 6.5cm, or that the height should have been 6.5cm, not 13cm. So, since you know how to do this now, you can figure out the correct answer.