Math Problem Statement

Calculate the total surface area of the following cone. Give your answer to one decimal place. The cone has a radius of 2 m and a slant height of 8 m.

Solution

To calculate the total surface area of the cone, we need to use the following formula for the surface area of a cone:

Total Surface Area=πr(r+l)\text{Total Surface Area} = \pi r (r + l)

where:

  • rr is the radius of the base,
  • ll is the slant height of the cone.

From the image:

  • Radius r=2r = 2 meters,
  • Slant height l=8l = 8 meters.

Now, substituting the values:

Total Surface Area=π×2×(2+8)\text{Total Surface Area} = \pi \times 2 \times (2 + 8) =π×2×10= \pi \times 2 \times 10 =20π= 20\pi

Calculating 20π20\pi with π3.1416\pi \approx 3.1416:

20×3.1416=62.8m220 \times 3.1416 = 62.8 \, \text{m}^2

Therefore, the total surface area of the cone is approximately:

Total Surface Area=62.8m2\text{Total Surface Area} = 62.8 \, \text{m}^2

Would you like further details on this calculation, or do you have any questions?

Here are some related questions that expand on this concept:

  1. How would the total surface area change if the slant height were different?
  2. What is the difference between the lateral surface area and the total surface area of a cone?
  3. How can we calculate the slant height if only the height and radius of the cone are given?
  4. What is the formula for the volume of a cone, and how is it derived?
  5. How does the surface area formula for a cone compare to that for a cylinder?

Tip: Remember, the slant height ll in cones is different from the vertical height. It always forms the hypotenuse of the right triangle formed by the radius and vertical height.

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Math Problem Analysis

Mathematical Concepts

Geometry
Surface Area Calculation

Formulas

Total Surface Area of a cone = πr(r + l)

Theorems

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Suitable Grade Level

Grades 8-10