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. 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?

She needs 301.8 in² of tissue paper.

Step-by-step explanation:

In order to calculate the amount of tissue paper she needs to make 21 hats, we need to find the area of each hat and multiply it by the total number of hats she wants to make.

Since the Vietnamese conical hats are hollow and don't have a base, we need to find the area of the it's lateral walls, this is given by the following expression:

lateral area = pi*r*l

r = d/2 = 16/2 = 8 in

We were given the height, but we need the slant height, therefore:

l = sqrt (r² + h²) = sqrt (8² + 9²) = sqrt (64 + 81) = sqrt (145) = 12.041 in

Then the lateral area is:

lateral area = pi*8*12.0141 = 301.8 in²

She needs 301.8 in² of tissue paper.