Call Now to Set Up Tutoring:

(888) 888-0446

Pre-Algebra : Area of a Circle

Study concepts, example questions & explanations for Pre-Algebra

Create An Account

All Pre-Algebra Resources

11 Diagnostic Tests 177 Practice Tests Question of the Day Flashcards Learn by Concept

Example Questions

Example Question #51 : Area Of A Circle

Determine the area of a circle with a radius of $4\pi$ .

Possible Answers:

$16\pi^2$

$16\pi^3$

$4\pi^4$

$4\pi^2$

$4\pi^3$

Correct answer:

$16\pi^3$

Explanation:

Write the equation to find the area of a circle.

$A=\pi r^2$

Substitute the radius.

$A=\pi (4\pi)^2 = \pi (16\pi^2) = 16\pi^3$

Report an Error

Example Question #52 : Area Of A Circle

Find the area of a circle if the radius is 24.

Possible Answers:

$48\pi$

$576 \pi$

$288\pi$

$72\pi$

$144\pi$

Correct answer:

$576 \pi$

Explanation:

Write the formula for the area of a circle.

$A=\pi r^2$

Substitute the radius.

When multiplying two digit numbers together remember to do it in steps.

$24\\ \underline{\times\ 24}$

First multiply $4\times 4=16$ , the six will stay in the ones place and the one will be carried to the tens place above the two.

${\color{Red} 2}4\\ \underline{\times\ 2{\color{Red} 4}}$

Now multiply four and the two (highlighted in red above) then add the one that was carried over.

$2\times 4=8+1=9$

This number goes next to the six.

$2{\color{Red}4}\\ \underline{\times\ {\color{Red} 2}4}$

Placing a zero in the ones places signifies that we are in our second step of multiplication. We will multiply the two and four (highlighted in red).

$2{\color{Red}4}\\ \underline{\times\ {\color{Red} 2}4}$

Now we will multiply two and two,

${\color{Red}2}4\\ \underline{\times\ {\color{Red} 2}4}$

480

From here add down to get the final product.

96+480=576

Therefore the final area is,

$A=\pi (24)^2 =576 \pi$ .

Report an Error

Example Question #53 : Area Of A Circle

Find the area of the circle if the radius is .

Possible Answers:

$25\pi$

$250\pi$

$100\pi$

$15625\pi$

$2500\pi$

Correct answer:

$2500\pi$

Explanation:

Substitute the radius into the formula for the area of a circle.

$A=\pi r^2 = \pi (50 )^2 = 2500\pi$

Report an Error

Example Question #54 : Area Of A Circle

Find the area of a circle if the radius is $2\sqrt2$ .

Possible Answers:

$8\pi$

$4\pi$

$6\pi$

$12\pi$

$16\pi$

Correct answer:

$8\pi$

Explanation:

Write the formula for the area of a circle.

$A=\pi r^2$

Substitute the radius into the formula.

Remember when squaring the radius, square both terms. Also recall that when two square roots that have the same base are multiplied together, the square root sign disappears and you are left with the number underneath the square root sign.

$(2\sqrt{2})^2=2^2\cdot \sqrt2\cdot \sqrt2=4\cdot 2$

Therefore the area becomes,

$A=\pi (2\sqrt2)^2 = \pi (4\times 2) = 8\pi$ .

Report an Error

Example Question #55 : Area Of A Circle

Find the area of a circle if the circle has a perimeter of .

Possible Answers:

$18\pi$

$\frac{9}{\pi}$

$6\pi$

$36\pi$

$\frac{6}{\pi}$

Correct answer:

$\frac{9}{\pi}$

Explanation:

The circle's perimeter is the same as the circle's circumference.

Write the circumference formula for the circle.

$C=2\pi r$

Substitute the circumference and solve for the radius.

$6=2\pi r$

$r=\frac{3}{\pi}$

Write the formula for the area of a circle.

$A=\pi r^2$

$A=\pi (\frac{3}{\pi})^2 = \pi (\frac{9}{\pi^2}) =\frac{9}{\pi}$

Report an Error

Example Question #56 : Area Of A Circle

Suppose the circle is inscribed inside a square touching all four sides of the square. The side length of the square is 2. What is the area of the circle?

Possible Answers:

$\frac{\pi}{2}$

$2\pi$

$\sqrt2 \pi$

$\pi$

$4\pi$

Correct answer:

$\pi$

Explanation:

Since the side of the square is 2, the diameter of the circle must also be 2. The radius of the circle is half the diameter, which would be 1.

Write the formula for the area of the circle.

$A=\pi r^2$

Substitute the radius.

$A=\pi r^2 = \pi (1)^2 = \pi$

Report an Error

Example Question #54 : Area Of A Circle

Solve for the area of a circle if the radius is .

Possible Answers:

$4\pi + \pi x^2$

$4\pi x$

$4\pi^2 x^2$

4+x^2

$4\pi x^2$

Correct answer:

$4\pi x^2$

Explanation:

Write the formula to find the area of a circle.

$A=\pi r^2$

Substitute the radius.

$A=\pi (2x)^2 = 4\pi x^2$

Report an Error

Example Question #58 : Area Of A Circle

Find the area of a circle with a diameter of .

Possible Answers:

$\frac{\pi x^2}{4}$

$\pi x^2$

$4\pi x^2$

$\frac{\pi x^2}{2}$

$2\pi x^2$

Correct answer:

$\frac{\pi x^2}{4}$

Explanation:

Write the area of the circle.

$A=\pi r^2$

The radius is half the diameter.

$r= \frac{d}{2} = \frac{x}{2}$

Substitute the radius into the area formula.

Remember that when a fraction is squared, both the numerator and denominator are squared.

$A=\pi \left(\frac{x}{2}\right)^2 = \pi (\frac{x\cdot x}{2\cdot 2})=\frac{\pi x^2}{4}$

Report an Error

Example Question #59 : Area Of A Circle

Solve for the area of the circle if the circumference is $16\pi$ .

Possible Answers:

$256\pi$

$96\pi$

$16\pi$

$64\pi$

$8\pi$

Correct answer:

$64\pi$

Explanation:

Write the formula for the circumference of a circle to find the radius.

$C=2\pi r$

$16\pi=2\pi r$

Divide by $2\pi$ on both sides of the equation.

$\frac{16\pi}{2\pi}=\frac{2\pi r}{2\pi}$

$\frac{2\pi \times 8}{2\pi}=\frac{2\pi r}{2\pi}$

Cancel out the $2\pi$ in the numerator and denominator. The radius is:

r=8

Write the formula for the area of a circle.

$A=\pi r^2$

Substitute the radius and find the area.

$A=\pi (8)^2 = \pi \cdot 8 \cdot 8 =64\pi$

Report an Error

Example Question #172 : Geometry

Find the area of a circle if the radius is $\sqrt7$ .

Possible Answers:

$\sqrt{7\pi}$

$7\pi$

$49\pi$

$\pi\sqrt7$

$\sqrt{\pi+7}$

Correct answer:

$7\pi$

Explanation:

Write the formula to find the area of a circle.

$A=\pi r^2$

Substitute the radius.

$A=\pi (\sqrt7)^2$

When a square root is squared, the square root is eliminated.

$(\sqrt x)^2 = (\sqrt x)(\sqrt x)=x$

Expand the terms.

$A=\pi (\sqrt7)^2 = \pi (\sqrt7)(\sqrt7) = 7\pi$

Report an Error

View Pre-Algebra Tutors

Matthew
Certified Tutor

Bluffton University, Bachelor of Education, Mathematics. Bluffton University, Masters in Education, Education.

View Pre-Algebra Tutors

Shrikar
Certified Tutor

University of South Florida-Main Campus, Bachelor of Science, Biomedical Sciences.

View Pre-Algebra Tutors

Donna
Certified Tutor

Indiana University of Pennsylvania-Main Campus, Bachelor of Science, Education of Developmentally Delayed Individuals. Grand ...

All Pre-Algebra Resources

11 Diagnostic Tests 177 Practice Tests Question of the Day Flashcards Learn by Concept

Popular Subjects

Physics Tutors in Atlanta, ISEE Tutors in Dallas Fort Worth, Math Tutors in Washington DC, Computer Science Tutors in Phoenix, Math Tutors in Philadelphia, English Tutors in Seattle, SAT Tutors in Washington DC, Physics Tutors in Washington DC, SSAT Tutors in Denver, MCAT Tutors in Miami

Popular Courses & Classes

GMAT Courses & Classes in New York City, GRE Courses & Classes in Miami, MCAT Courses & Classes in San Diego, GRE Courses & Classes in New York City, ACT Courses & Classes in Los Angeles, SSAT Courses & Classes in Washington DC, Spanish Courses & Classes in Chicago, LSAT Courses & Classes in Chicago, ACT Courses & Classes in Phoenix, GMAT Courses & Classes in Los Angeles

Popular Test Prep

SSAT Test Prep in Los Angeles, SAT Test Prep in Atlanta, ACT Test Prep in Phoenix, MCAT Test Prep in San Francisco-Bay Area, SAT Test Prep in Phoenix, SAT Test Prep in Philadelphia, GMAT Test Prep in Denver, ISEE Test Prep in Boston, GMAT Test Prep in New York City, SSAT Test Prep in Miami

DMCA Complaint

If you believe that content available by means of the Website (as defined in our Terms of Service) infringes one or more of your copyrights, please notify us by providing a written notice (“Infringement Notice”) containing the information described below to the designated agent listed below. If Varsity Tutors takes action in response to an Infringement Notice, it will make a good faith attempt to contact the party that made such content available by means of the most recent email address, if any, provided by such party to Varsity Tutors.

Your Infringement Notice may be forwarded to the party that made the content available or to third parties such as ChillingEffects.org.

Please be advised that you will be liable for damages (including costs and attorneys’ fees) if you materially misrepresent that a product or activity is infringing your copyrights. Thus, if you are not sure content located on or linked-to by the Website infringes your copyright, you should consider first contacting an attorney.

Please follow these steps to file a notice:

You must include the following:

A physical or electronic signature of the copyright owner or a person authorized to act on their behalf; An identification of the copyright claimed to have been infringed; A description of the nature and exact location of the content that you claim to infringe your copyright, in \ sufficient detail to permit Varsity Tutors to find and positively identify that content; for example we require a link to the specific question (not just the name of the question) that contains the content and a description of which specific portion of the question – an image, a link, the text, etc – your complaint refers to; Your name, address, telephone number and email address; and A statement by you: (a) that you believe in good faith that the use of the content that you claim to infringe your copyright is not authorized by law, or by the copyright owner or such owner’s agent; (b) that all of the information contained in your Infringement Notice is accurate, and (c) under penalty of perjury, that you are either the copyright owner or a person authorized to act on their behalf.

Send your complaint to our designated agent at:

Charles Cohn Varsity Tutors LLC
101 S. Hanley Rd, Suite 300
St. Louis, MO 63105

Or fill out the form below:

Do not fill in this field

Contact Information

* Full legal name

Company name

* Phone number

* Email address

Address

* Address1

Address2

* City

* State

* Zipcode

* Country

Complaint Details

* URL of copyrighted work (where your original material is located)

* Please describe the copyrighted work so that it may be easily identified

I am the owner, or an agent authorized to act on behalf of the owner of an exclusive right that is allegedly infringed.

I have a good faith belief that the use of the material in the manner complained of is not authorized by the copyright owner, its agent, or the law.

This notification is accurate.

I acknowledge that there may be adverse legal consequences for making false or bad faith allegations of copyright infringement by using this process.

* Signature (your digital signature is legally binding)

HIGH SCHOOL

GRADUATE SCHOOL

K-8

Search 50+ Tests

math tutoring

science tutoring

foreign languages

elementary tutoring

other

Search 350+ Subjects

Pre-Algebra : Area of a Circle

Study concepts, example questions & explanations for Pre-Algebra

All Pre-Algebra Resources

Example Questions

Example Question #51 : Area Of A Circle

Example Question #52 : Area Of A Circle

Example Question #53 : Area Of A Circle

Example Question #54 : Area Of A Circle

Example Question #55 : Area Of A Circle

Example Question #56 : Area Of A Circle

Example Question #54 : Area Of A Circle

Example Question #58 : Area Of A Circle

Example Question #59 : Area Of A Circle

Example Question #172 : Geometry

All Pre-Algebra Resources

Report an issue with this question

DMCA Complaint

Contact Information

Address

Complaint Details

Email address:
Your name:
Feedback: