# How Do You Find the Surface Area of a Cone?

Calculate the surface area of a cone by first finding the area of the slanted section on top and the area of the base. Add these two areas together to get the total surface area of the cone.

1. Find the surface area of the top of the cone

To find the surface area of the top of the cone, multiply the radius of the base of the cone by the slant height. Next, multiply this number by pi. For example, if the base of the cone has a radius of 4 inches and a slant height of 9 inches, then multiply 4 times 9 times 3.14159 to get the surface area of the top of the cone, which is 113.1 square inches.

2. Find the surface area of the base of the cone

Multiply the radius of the base by pi squared. In the previous example, multiply 4 times pi squared to get the surface area of the base of the cone, which is 39.5 square inches.

3. Add the surface areas of the top and the bottom of the cone

To find the total surface area of the cone, add the surface area of the top to the surface area of the bottom.

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