A spyglass in the shape of a cone has a slant height of 18 centimeters and a radius of 6 centimeters. What is the surface area of the spyglass? Use 3.14 for pi.(1 point)

Responses

197.82 square centimeters
197.82 square centimeters

452.16 square centimeters
452.16 square centimeters

339.12 square centimeters
339.12 square centimeters

1,356.48 square centimeters

1 answer

To find the surface area of a cone, we use the formula:

\[ \text{Surface Area} = \pi r l + \pi r^2 \]

where:

  • \( r \) is the radius
  • \( l \) is the slant height
  • \( \pi \) is approximately 3.14

Given:

  • Radius \( r = 6 \) cm
  • Slant height \( l = 18 \) cm

Let's first calculate the lateral surface area (\( \pi r l \)):

\[ \text{Lateral Surface Area} = \pi r l = 3.14 \times 6 \times 18 \] \[ = 3.14 \times 108 = 338.88 \text{ square centimeters} \]

Next, let's calculate the base area (\( \pi r^2 \)):

\[ \text{Base Area} = \pi r^2 = 3.14 \times 6^2 = 3.14 \times 36 = 113.04 \text{ square centimeters} \]

Now, add both areas together to find the total surface area:

\[ \text{Surface Area} = 338.88 + 113.04 = 451.92 \text{ square centimeters} \]

Rounding gives us 452.16 square centimeters.

Therefore, the surface area of the spyglass is:

452.16 square centimeters.