what is the surface area in square centimeters of a cone with a diameter of 12 ft and a slant height of 14 ft. Use 3.14 for pi

1 answer

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

\[ \text{Surface Area} = \pi r (r + l) \]

where:

  • \( r \) is the radius of the base,
  • \( l \) is the slant height,
  • \( \pi \) is approximately \( 3.14 \).
  1. First, we need to find the radius. The diameter of the cone is given as 12 feet, so the radius \( r \) will be:

\[ r = \frac{\text{diameter}}{2} = \frac{12 \text{ ft}}{2} = 6 \text{ ft} \]

  1. The slant height \( l \) is given as 14 ft.

  2. Now, we can substitute the values of \( r \) and \( l \) into the surface area formula:

\[ \text{Surface Area} = \pi r (r + l) = 3.14 \times 6 \text{ ft} \times (6 \text{ ft} + 14 \text{ ft}) \]

  1. Calculate \( r + l \):

\[ r + l = 6 \text{ ft} + 14 \text{ ft} = 20 \text{ ft} \]

  1. Now substitute this into the surface area formula:

\[ \text{Surface Area} = 3.14 \times 6 \text{ ft} \times 20 \text{ ft} \]

  1. Calculate the surface area:

\[ \text{Surface Area} = 3.14 \times 6 \times 20 = 3.14 \times 120 = 376.8 \text{ ft}^2 \]

  1. Finally, since the question asks for the surface area in square centimeters, we need to convert square feet to square centimeters. We know that:

\[ 1 \text{ ft}^2 = 929.0304 \text{ cm}^2 \]

So:

\[ \text{Surface Area in cm}^2 = 376.8 \text{ ft}^2 \times 929.0304 \text{ cm}^2/\text{ft}^2 \]

Calculating this:

\[ \text{Surface Area in cm}^2 \approx 376.8 \times 929.0304 \approx 350,113.78 \text{ cm}^2 \]

Thus, the surface area of the cone is approximately:

\[ \boxed{350,113.78 \text{ cm}^2} \]