Practice Test
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Use the formula for the surface area of a cylinder.
Lateral Area: About 52.8 square inches
Surface Area: About 65.1 square inches
A circular pillar candle can be modeled by the following cylinder.
The height of the cylinder is h= 6 inches. Since the diameter of the base is 2.8 inches, the radius of the cylinder is r= 2.82= 1.4 inches. We are asked to find lateral and surface areas of the candle. Let's do it!
| Area | Lateral | Surface |
|---|---|---|
| Radius | r= 1.4 | |
| Height | h= 6 | |
| Formula | L=2Ï€ r h | S=2Ï€ r h+2Ï€ r^2 |
| L=2Ï€( 1.4)( 6)=16.8Ï€ | S=2Ï€( 1.4)( 6)+2Ï€( 1.4)^2=20.72Ï€ | |
| L≈ 52.8 | S≈ 65.1 | |
Therefore, the lateral area is about 52.8 square inches, and the surface area is about 65.1 square inches.