High School Math : High School Math

Study concepts, example questions & explanations for High School Math

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Example Questions

Example Question #751 : High School Math

What is the area of a circle with a radius of \displaystyle 12?

Possible Answers:

\displaystyle A=12\pi

\displaystyle A=188\pi

\displaystyle A=144\pi

\displaystyle A=24\pi

Correct answer:

\displaystyle A=144\pi

Explanation:

To find the area of a circle you must plug the radius into  in the following equation

In this case the radius is \displaystyle 12 so we plug it into  to get 

\displaystyle A=12^{2}\pi

We then multiply it by  to get our answer 

\displaystyle A=144\pi.

Example Question #17 : How To Find The Area Of A Circle In Pre Algebra

What is the area of a circle with a radius of \displaystyle 7?

Possible Answers:

\displaystyle A=7\pi

\displaystyle A=42\pi

\displaystyle A=14\pi

Correct answer:

Explanation:

To find the area of a circle you must plug the radius into  in the following equation

In this case the radius is \displaystyle 7 so we plug it into  to get

We then multiply it by  to get our answer .

Example Question #751 : High School Math

What is the radius of a circle with an area of \displaystyle 144\pi?

Possible Answers:

\displaystyle 6

\displaystyle 12

\displaystyle 72

\displaystyle 24

\displaystyle 144

Correct answer:

\displaystyle 12

Explanation:

The formula for the area of a circle is \displaystyle A=\pi r^2.

Plug in our given values.

\displaystyle A=\pi r^2

\displaystyle 144\pi=\pi r^2

Notice the \displaystyle \pi's cancel out. 

\displaystyle 144=r^2

\displaystyle \sqrt{144}=\sqrt{r^2}

\displaystyle 12=r

Example Question #471 : Pre Algebra

What is the diameter of a circle with an area of \displaystyle 169\pi?

Possible Answers:

\displaystyle 13

\displaystyle 84.5

\displaystyle 26

\displaystyle 13\pi

\displaystyle 26\pi

Correct answer:

\displaystyle 26

Explanation:

The formula for the area of a circle is \displaystyle A=\pi r^2.

Plug in our given values.

\displaystyle A=\pi r^2

\displaystyle 169\pi=\pi r^2

Notice that the pi cancels out.

\displaystyle 169=r^2

\displaystyle \sqrt{169}=\sqrt{r^2}

\displaystyle 13=r

The diameter is twice the radius or \displaystyle d=2r.

For this circle that means that \displaystyle d=2*13=26.

Example Question #751 : High School Math

What is the area of circle with a radius of \displaystyle 7?

Possible Answers:

\displaystyle 7\pi

\displaystyle 49\pi

\displaystyle 14\pi

\displaystyle 70\pi

Correct answer:

\displaystyle 49\pi

Explanation:

To find the area of a circle, use the equation:

\displaystyle Area=\pi(radius^{2})

Substitute the given value for radius:

\displaystyle Area=\pi(7^{2})

\displaystyle Area=49\pi

Example Question #752 : High School Math

Find the area of a circle with a radius of 12 inches.

Possible Answers:

\displaystyle 112\pi \ in^{2}

\displaystyle 144\pi \ in^{2}

\displaystyle 12\pi \ in^{2}

\displaystyle 48\pi \ in^{2}

\displaystyle 24\pi \ in^{2}

Correct answer:

\displaystyle 144\pi \ in^{2}

Explanation:

The formula for the area of a circle is \displaystyle A=\pi r^2.

Plug your radius value in and you get \displaystyle 144\pi.

Make sure your units are squared.

Example Question #753 : High School Math

What is the area of a circle with diameter \displaystyle 6?

Possible Answers:

\displaystyle 9\pi

\displaystyle 6\pi

\displaystyle 12\pi

\displaystyle 3\pi

\displaystyle 9

Correct answer:

\displaystyle 9\pi

Explanation:

The area of a circle is calculated with the equation \displaystyle A=\pi r^2.

\displaystyle r is half of the diameter, which in our case is 3.

\displaystyle A=\pi r^2= (3)^2\pi=9\pi

Example Question #754 : High School Math

Find the area of a circle with a radius of 7 inches.

Possible Answers:

\displaystyle 14\pi \ in^{2}

\displaystyle 149\pi \ in^{2}

\displaystyle 117\pi \ in^{2}

\displaystyle 7\pi \ in^{2}

\displaystyle 49\pi \ in^{2}

Correct answer:

\displaystyle 49\pi \ in^{2}

Explanation:

Use the formula for the area of a circle, \displaystyle A=\pi r^{2}, and plug in 7 for the radius to get \displaystyle 49\pi. Make sure your answer is in units squared. 

Example Question #755 : High School Math

Find the area of a circle with a circumference of \displaystyle 26\pi.

Possible Answers:

\displaystyle 169\pi

\displaystyle 52\pi

\displaystyle 225

\displaystyle 13\pi

\displaystyle 26\pi

Correct answer:

\displaystyle 169\pi

Explanation:

The circumference equation is \displaystyle C = 2\pi r

If we plug \displaystyle 26\pi into the equation, we can solve for the radius, which is \displaystyle 13.

 

Now, we look for the area of the circle based on the equation \displaystyle A = \pi r^{2}

\displaystyle A = 169\pi

Example Question #25 : How To Find The Area Of A Circle In Pre Algebra

The area of a circle is \displaystyle 49 \pi . What is its radius? 

Possible Answers:

\displaystyle 21

\displaystyle 14

\displaystyle 3.5

\displaystyle 49

\displaystyle 7

Correct answer:

\displaystyle 7

Explanation:

Here, we are given the area of a circle and asked to solve for the radius. We know that the formula for the area of a circle is\displaystyle A = \pi(r)^{2}

Plugging in the area, we can cancel out the pi on each side of the equation, so that 

\displaystyle r^{2} = 49

Taking the square root, we find that \displaystyle r = 7

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