Find the surface area of a cone with a diameter of 16 inches and a slant height of 9 inches. Use 3.14 for pi

1 answer

To find 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 of the base of the cone, and \( l \) is the slant height.

  1. Find the radius: The diameter of the cone is 16 inches, so the radius \( r \) is:

\[ r = \frac{\text{diameter}}{2} = \frac{16}{2} = 8 \text{ inches} \]

  1. Given slant height: The slant height \( l \) is given as 9 inches.

  2. Calculate the surface area: Now we can substitute the values into the surface area formula:

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

First, calculate \( \pi r^2 \):

\[ \pi r^2 = 3.14 \times (8^2) = 3.14 \times 64 = 200.96 \text{ square inches} \]

Next, calculate \( \pi r l \):

\[ \pi r l = 3.14 \times 8 \times 9 = 3.14 \times 72 = 226.08 \text{ square inches} \]

  1. Add both areas:

\[ \text{Surface Area} = 200.96 + 226.08 = 427.04 \text{ square inches} \]

Thus, the surface area of the cone is:

\[ \boxed{427.04} \text{ square inches} \]