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If a circle has area 169pie square inches, what is the radius?

The area of a circle with radius r is given by the formula A="pie"r^2. If a circle has area 169"pie square inches, what is the radius?

Well, the formula for area is:
A=pi*r^2
So, let’s plug in what A is:
169pi=pi*r^2
We can divide each side by pi to get rid of it:
169=r^2
r=13 or -13, depending what quadrant you’re in.

Have a nice day now :-)

This entry was posted on Sunday, April 11th, 2010 at 6:18 pm and is filed under circle area. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

2 Responses to “If a circle has area 169pie square inches, what is the radius?”

  1. divide both sides by pi. r^2 is 169, so the square root of 169 is 13.
    and thats your answer.
    References :

  2. Well, the formula for area is:
    A=pi*r^2
    So, let’s plug in what A is:
    169pi=pi*r^2
    We can divide each side by pi to get rid of it:
    169=r^2
    r=13 or -13, depending what quadrant you’re in.

    Have a nice day now :-)
    References :
    Grade 10 Math

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