Math Problem Statement

A sphere and a cone are shown. The surface area of the sphere is the same as the curved surface area of the cone. Given that the radius of the sphere is 6 m and the base diameter of the cone is 8 m, calculate the slant height of the cone to 1 decimal place.

Solution

Let's solve the problem step by step.

Given:

  • Sphere radius r=6r = 6 m.
  • Cone base diameter = 8 m, so cone radius r=4r = 4 m.
  • The surface area of the sphere is equal to the curved surface area of the cone.

Step 1: Find the Surface Area of the Sphere

The formula for the surface area of a sphere is: A=4πr2A = 4\pi r^2 Substituting r=6r = 6:

A=4π(62)=144π m2A = 4\pi (6^2) = 144\pi \text{ m}^2

Step 2: Find the Curved Surface Area of the Cone

The curved surface area of a cone is given by:

A=πrlA = \pi r l

where r=4r = 4 m and ll is the slant height.

Since this is equal to the sphere’s surface area:

π(4)l=144π\pi (4) l = 144\pi

Cancel π\pi on both sides:

4l=1444l = 144

Step 3: Solve for ll

l=1444=36 ml = \frac{144}{4} = 36 \text{ m}

Final Answer:

The slant height of the cone is 36.0 m (to 1 decimal place).


Would you like a breakdown of any step? Here are some related questions you might find interesting:

  1. How do we derive the formula for the surface area of a sphere?
  2. What is the full surface area (including the base) of the cone?
  3. How do we calculate the volume of the cone and the sphere?
  4. How does changing the radius of the cone affect the slant height?
  5. What real-life applications involve using curved surface areas?

Tip: Always check if given dimensions are radii or diameters to avoid calculation mistakes!

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Math Problem Analysis

Mathematical Concepts

Surface Area
Geometry of Spheres and Cones
Algebraic Manipulation

Formulas

Surface area of a sphere: 4πr²
Curved surface area of a cone: πrl

Theorems

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Suitable Grade Level

Grades 8-10