Find the surface area of the cone. The diameter is 16, and the slant height is 9. Use 3.14 for pi.

1 answer

To find the surface area of a cone, we need to calculate both the lateral surface area and the base area. The formula for the total surface area \( A \) of a cone is given by:

\[ A = \pi r l + \pi r^2 \]

where:

  • \( r \) is the radius,
  • \( l \) is the slant height.

First, we need to find the radius from the diameter. The diameter is given as 16, so:

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

Next, we know the slant height \( l \) is given as 9.

Now we can calculate the two areas:

  1. Lateral Surface Area: \[ \text{Lateral Surface Area} = \pi r l = 3.14 \times 8 \times 9 \]

Calculating this step-by-step:

\[ 8 \times 9 = 72 \] \[ 3.14 \times 72 = 226.08 \]

Thus, the lateral surface area is \( 226.08 \).

  1. Base Area: \[ \text{Base Area} = \pi r^2 = 3.14 \times (8^2) \]

Calculating \( 8^2 \):

\[ 8^2 = 64 \]

Now multiplying:

\[ 3.14 \times 64 = 200.96 \]

Thus, the base area is \( 200.96 \).

  1. Total Surface Area: Adding the lateral surface area and the base area together:

\[ A = \text{Lateral Surface Area} + \text{Base Area} \] \[ A = 226.08 + 200.96 = 427.04 \]

Therefore, the total surface area of the cone is:

\[ \boxed{427.04} \]