Question

easy points, need help with this question due tomorrow. the formula is given but im not sure how to solve, help?

Answer 1

Approximated: 358.14 cm²

Exact: 358.141562509 cm²

Explanation:

Hello!

The formula given with the question is only for the Curved Surface Area of a cone. Remember that the cone still has a circular base!

Curved Surface Area

We have the formula and the value to solve for the curved surface area.

Solve

• 
  `A = \pi rl`
• 
  `A = \pi(6)(13)`
• 
  `A = 78\pi`
• 
  `A = 245.04422698 \approx 245.04`

Base Area

Now, we just have to solve for the circular base and add the two values for the total area.

Formula:
`A = \pi r^2`

Solve

• 
  `A = \pi r^2`
• 
  `A = \pi (6^2)`
• 
  `A = 36\pi`
• 
  `A = 113.097335529 \approx 113.1`

Surface Area

Now we can add the two values to get a total of 358.14cm².

Another way to be a little more precise was to add 78π and 36π directly, but it still rounds to around the same value.