High School Math : How to find the surface area of a sphere

Study concepts, example questions & explanations for High School Math

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Example Questions

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Example Question #1 : How To Find The Surface Area Of A Sphere

What is the surface area of a sphere with a radius of 15?

Possible Answers:

Correct answer:

Explanation:

To solve for the surface area of a sphere you must use the equation

First, plug in 15 for  and square it

 

Multiply by 4 and  to get

 

The answer is .

Example Question #2 : How To Find The Surface Area Of A Sphere

What is the surface area of a sphere whise radius is .

Possible Answers:

Not enough information to solve

Correct answer:

Explanation:

The surface area of a sphere is found by the formula  using the given radius of .

Example Question #3 : How To Find The Surface Area Of A Sphere

Find the surface area of a sphere whose diameter is .

Possible Answers:

Correct answer:

Explanation:

The surface area of a sphere is found by the formula . We need to first convert the given diameter of  to the sphere's radius.

Now, we can solve for surface area.

Example Question #4 : How To Find The Surface Area Of A Sphere

To the nearest tenth of a square centimeter, give the surface area of a sphere with volume 1,000 cubic centimeters.

Possible Answers:

Correct answer:

Explanation:

The volume of a sphere in terms of its radius  is 

Substitute  and solve for :

Substitute for  in the formula for the surface area of a sphere:

Example Question #5 : How To Find The Surface Area Of A Sphere

Find the surface area of a sphere with a radius of

Possible Answers:

Correct answer:

Explanation:

The standard equation to find the area of a sphere is .

Substitute the given radius into the standard equation to get the answer:

Example Question #6 : How To Find The Surface Area Of A Sphere

Given that the radius of a sphere is 3, find the surface area. 

Possible Answers:

Correct answer:

Explanation:

The standard equation to find the area of a sphere is 

where  denotes the radius. Plug in the given radius to find the surface area. 

Example Question #7 : How To Find The Surface Area Of A Sphere

Find the surface area of the following sphere.

Sphere

Possible Answers:

Correct answer:

Explanation:

The formula for the surface area of a sphere is:

where  is the radius of the sphere.

 

Plugging in our values, we get:

Example Question #8 : How To Find The Surface Area Of A Sphere

Find the surface area of the following sphere.

Sphere

Possible Answers:

Correct answer:

Explanation:

The formula for the surface area of a sphere is:

Where  is the radius of the sphere

 

Plugging in our values, we get:

Example Question #1 : How To Find The Surface Area Of A Sphere

What is the surface area of a composite figure of a cone and a sphere, both with a radius of 5 cm, if the height of the cone is 12 cm? Consider an ice cream cone as an example of the composite figure, where half of the sphere is above the edge of the cone.

Possible Answers:

Correct answer:

Explanation:

Calculate the slant height height of the cone using the Pythagorean Theorem. The height will be the height of the cone, the base will be the radius, and the hypotenuse will be the slant height.

The surface area of the cone (excluding the base) is given by the formula . Plug in our values to solve.

The surface area of a sphere is given by  but we only need half of the sphere, so the area of a hemisphere is .

So the total surface area of the composite figure is .

Example Question #687 : Geometry

What is the surface area of a hemisphere with a diameter of 4\ cm?

Possible Answers:

Correct answer:

Explanation:

A hemisphere is half of a sphere.  The surface area is broken into two parts:  the spherical part and the circular base. 

The surface area of a sphere is given by SA = 4\pi r^{2}.

So the surface area of the spherical part of a hemisphere is SA = 2\pi r^{2}

The area of the circular base is given by A = \pi r^{2}.  The radius to use is half the diameter, or 2 cm.

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