SSAT Upper Level Math : How to find the area of a circle

Study concepts, example questions & explanations for SSAT Upper Level Math

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Example Questions

Example Question #21 : Geometry

You have a circular yard and want to cover it with new sod.  If you walk from the center to the fence, it is 11 feet.  What would be the area of the sod?

Possible Answers:

Correct answer:

Explanation:

To find the area of a circle, the equation is .  

The  is the radius or the distance from the center to the outside of the circle.  

You would plug in the  in for  and that gives you an area of .

Example Question #21 : How To Find The Area Of A Circle

What is the area of a circle with a diameter of , rounded to the nearest whole number?

Possible Answers:

\dpi{100} 255

\dpi{100} 81

\dpi{100} 254

\dpi{100} 64

Correct answer:

\dpi{100} 64

Explanation:

The formula for the area of a circle is

\dpi{100} \pi r^{2}

Find the radius by dividing 9 by 2:

\dpi{100} \frac{9}{2}=4.5

So the formula for area would now be:

\dpi{100} \pi r^{2}=\pi (4.5)^{2}=20.25\pi \approx 63.6= 64

Example Question #22 : Area And Circumference Of A Circle

Untitled

In the above diagram, the area of the shaded sector is . Evaluate .

Possible Answers:

Correct answer:

Explanation:

The area of the entire circle is equal to  multiplied by the square of the radius, or

The shaded  sector is equal in area to 

that of the entire circle, so 

Solving for :

Example Question #21 : How To Find The Area Of A Circle

Find the area of a circle with a radius of 4.

 

Possible Answers:

Correct answer:

Explanation:

The formula for the area of a circle is as follows:

In this formula, A is area, and r is for radius. We know the radius of the circle is 4, so plug in the numbers to get the answer. Since pi is an irrational constant, it is okay to leave the answer in terms of pi.

Example Question #22 : How To Find The Area Of A Circle

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

Possible Answers:

Correct answer:

Explanation:

The formula for the area of a circle is as follows:

In this formula, A is area, and r is for radius. We know the radius of the circle is 12, so plug in the numbers to get the answer. Since pi is an irrational constant, it is okay to leave the answer in terms of pi.

Example Question #23 : How To Find The Area Of A Circle

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

Possible Answers:

Correct answer:

Explanation:

The formula for the area of a circle is as follows:

In this formula, A is area, and r is for radius. We know the radius of the circle is 7, so plug in the numbers to get the answer. Since pi is an irrational constant, it is okay to leave the answer in terms of pi.

Example Question #24 : How To Find The Area Of A Circle

Find the area of a circle with a radius of 5.

Possible Answers:

Correct answer:

Explanation:

The formula for the area of a circle is as follows:

In this formula, A is area, and r is for radius. We know the radius of the circle is 5, so plug in the numbers to get the answer. Since pi is an irrational constant, it is okay to leave the answer in terms of pi.

Example Question #25 : Geometry

Find the area of a circle with a diameter of 6.

Possible Answers:

Correct answer:

Explanation:

The formula for the area of a circle is as follows:

In this formula, A is area, and r is for radius. We know the diameter of the circle is 6, meaning we have to first find the radius. The diameter is twice the length of the radius of a circle, meaning to find radius divide the diameter by 2:

Now plug in the numbers to get the answer. Since pi is an irrational constant, it is okay to leave the answer in terms of pi.

Example Question #26 : Area And Circumference Of A Circle

Find the area of a circle with a diameter of 16.

Possible Answers:

Correct answer:

Explanation:

The formula for the area of a circle is as follows:

In this formula, A is area, and r is for radius. We know the diameter of the circle is 16, meaning we have to first find the radius. The diameter is twice the length of the radius of a circle, meaning to find radius divide the diameter by 2:

Now plug in the numbers to get the answer. Since pi is an irrational constant, it is okay to leave the answer in terms of pi.

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