Question

A water cup is shaped like a cone. It had a diameter of 3 inches and a slant height of 5 inches. About how many square inches of paper do you need to make a cup? Use 3.14 to approximate pi.

A. 24 square inches
B. 31 square inches
C. 47 square inches
D. 52 square inches

Answer 1

To find the surface area of the cone-shaped water cup, we need to calculate the lateral surface area, which is the area of the paper needed to make the cup.

The lateral surface area of a cone can be calculated using the formula:

Lateral Surface Area = π * r * slant height

First, we need to find the radius of the cone. The diameter is 3 inches, so the radius is half of that, which is 1.5 inches.

Using the given values:
Lateral Surface Area = 3.14 * 1.5 * 5
Lateral Surface Area = 23.55 square inches

Therefore, we need approximately 24 square inches of paper to make the cup.

So, the answer is:
A. 24 square inches.