Geometry HW that I need help with in the next 10 minutes.

Question

 Nguyen is decorating the room for her sister's baby shower party. She is wrapping Vietnamese conical hats in baby prints tissue paper to decorate the tables and some shelves in the wall. The hats are shaped like a cone with no base. Each hat has a diameter of 16 inches and a height of 9 inches. If she wants to wrap 21 Vietnamese hats, how much tissue paper will she need?

Answer 1

The surface area of the cone has formula

pi * radius * ( radius + sqrt ( height^2 + radius^2)) =

pi * radius^2 + pi * radius * sqrt( height^2 + radius^2)

However, this includes the base of the cone and the hats do NOT have

that. "The hats are shaped like a cone with NO BASE", says the 3rd sentence.

So the formula becomes pi * radius * sqrt( height^2 + radius^2)

diameter = 16

radius = 8

height = 9

The surface area of ONE of the hats is pi * 8 * sqrt( 9^2 + 8^2)

= pi * 8 * sqrt( 81+64)

= pi * 8 * sqrt(145)

302.63828053.....

21 of them is 21 * 302... = 6355.40689112841343251026086.....