IXL | Surface area of cones

What is the surface area of this cone?

Round your answer to the nearest hundredth.

3 in

2 in

square inches

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Learn with an example

question

What is the surface area of this cone?

Round your answer to the nearest hundredth.

9 m

4 m

square meters

key idea

Surface area of a cone:

Surface area

L.A.

area of base

lateral area

𝜋

A cone's slant height, s, is the distance between the vertex and any point on the circular base.

solution

Find the radius and slant height of the cone.

radius

slant height

Find the area of the base. Use 𝜋 ≈ 3.14.

Area of base

𝜋r²

≈

3.14 × 4²

≈

50.24

Find the lateral area.

Lateral area

𝜋rs

≈

3.14 × 4 × 9

≈

113.04

Now add the areas to find the surface area of the cone.

Surface area

area of base + lateral area

≈

50.24 + 113.04

≈

163.28

The surface area of the cone is about 163.28 square meters.

Looking for more? Try these:

Lesson: Surface area formulas

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