What is the surface area, in square inches, of a cone with a radius of 10 inches and a slant height of 15 inches? Use 3.14 for pi.(1 point) Responses 1,177.5 square inches 1,177.5 square inches 471 square inches 471 square inches 2,198 square inches 2,198 square inches 785 square inches

1 answer

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

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

where \( r \) is the radius and \( l \) is the slant height.

Given:

  • Radius, \( r = 10 \) inches
  • Slant height, \( l = 15 \) inches
  • Using \( \pi \approx 3.14 \)

We first calculate the base area:

\[ \text{Base Area} = \pi r^2 = 3.14 \times (10)^2 = 3.14 \times 100 = 314 \text{ square inches} \]

Next, we calculate the lateral surface area:

\[ \text{Lateral Surface Area} = \pi r l = 3.14 \times 10 \times 15 = 3.14 \times 150 = 471 \text{ square inches} \]

Now, we add the base area and the lateral surface area to find the total surface area:

\[ \text{Total Surface Area} = \text{Base Area} + \text{Lateral Surface Area} = 314 + 471 = 785 \text{ square inches} \]

Therefore, the surface area of the cone is

\[ \boxed{785} \text{ square inches} \]