Basic Geometry : Circles

Study concepts, example questions & explanations for Basic Geometry

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Example Questions

Example Question #45 : Radius

A car tire has a radius of 18 inches. When the tire has made 200 revolutions, how far has the car gone in feet?

Possible Answers:

300π

3600π

600π

500π

Correct answer:

600π

Explanation:

If the radius is 18 inches, the diameter is 3 feet. The circumference of the tire is therefore 3π by C=d(π). After 200 revolutions, the tire and car have gone 3π x 200 = 600π feet.

Example Question #46 : Radius

A circle has the equation below. What is the circumference of the circle?

(x – 2)2 + (y + 3)2 = 9

Possible Answers:

Correct answer:

Explanation:

The radius is 3. Yielding a circumference of .

Example Question #3 : Circumference Of A Circle

If a circle has an area of , what is the circumference?

Possible Answers:

Correct answer:

Explanation:

For a circle, the formula for area is  and the formula for circumference is , where  is the radius and  is the diameter.

Plug the known quantities into the area formula and solve for the radius:

 

Now plug this value into the circumference formula to solve:

Example Question #201 : Plane Geometry

Line  is the radius of the circle shown and has a length of 7.5. What is the circumference of the circle?

Circle

Possible Answers:

Correct answer:

Explanation:

Plug in the given value for the radius to find the circumference:

 

Example Question #4 : Circumference Of A Circle

Find the circumference of a circle with a radius of .

Possible Answers:

Correct answer:

Explanation:

Recall the formula for finding the circumference of a circle:

We can substitute in the value for the radius in order to find the circumference of the circle in question.

Solve.

Simplify.

Example Question #4 : Circumference Of A Circle

Find the circumference of a circle that has a radius of .

Possible Answers:

Correct answer:

Explanation:

Recall the formula for finding the circumference of a circle:

We can substitute in the value for the radius in order to find the circumference of the circle in question.

Solve.

Simplify.

Example Question #5 : Circumference Of A Circle

Find the circumference of the circle with a radius of .

Possible Answers:

Correct answer:

Explanation:

Recall the formula for finding the circumference of a circle:

We can substitute in the value for the radius in order to find the circumference of the circle in question.

Solve.

Simplify.

Example Question #6 : Circumference Of A Circle

Find the circumference of a circle with a radius of .

Possible Answers:

Correct answer:

Explanation:

Recall the formula for finding the circumference of a circle:

We can substitute in the value for the radius in order to find the circumference of the circle in question.

Solve.

Simplify.

Example Question #202 : Basic Geometry

Find the circumference of a circle with a radius of .

Possible Answers:

Correct answer:

Explanation:

Recall the formula for finding the circumference of a circle:

We can substitute in the value for the radius in order to find the circumference of the circle in question.

Solve.

Simplify.

Example Question #203 : Basic Geometry

Find the circumference of a circle with a radius of .

Possible Answers:

Correct answer:

Explanation:

Recall the formula for finding the circumference of a circle:

We can substitute in the value for the radius in order to find the circumference of the circle in question.

Solve.

Simplify.

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