What is the surface area of this cone?

Use ​𝜋 ≈ 3.14 and round your answer to the nearest hundredth.

16 mm
14 mm

square millimeters

1 answer

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

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

Where:

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

In this problem:

  • The height of the cone \( h = 16 \) mm,
  • The radius of the base \( r = 14 \) mm.

First, we need to find the slant height \( l \) using the Pythagorean theorem:

\[ l = \sqrt{r^2 + h^2} \]

Calculating \( l \):

\[ l = \sqrt{(14)^2 + (16)^2} = \sqrt{196 + 256} = \sqrt{452} \]

Calculating \( \sqrt{452} \):

\[ \sqrt{452} \approx 21.26 , \text{mm} \]

Next, we can substitute \( r \) and \( l \) into the surface area formula.

Calculating the base area:

\[ \pi r^2 = \pi (14)^2 = \pi \cdot 196 \approx 3.14 \cdot 196 \approx 384.64 , \text{mm}^2 \]

Calculating the lateral surface area:

\[ \pi r l = \pi \cdot 14 \cdot 21.26 \approx 3.14 \cdot 14 \cdot 21.26 \]

Calculating \( 14 \cdot 21.26 \):

\[ 14 \cdot 21.26 \approx 297.64 \]

Now substituting it into the equation:

\[ \pi r l \approx 3.14 \cdot 297.64 \approx 934.47 , \text{mm}^2 \]

Now, adding both areas together for total surface area:

\[ \text{Surface Area} \approx 384.64 + 934.47 \approx 1319.11 , \text{mm}^2 \]

Hence, the surface area of the cone is approximately:

\[ \boxed{1319.11} , \text{mm}^2 \]