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I need help, please and thank you. I know that you have to multiply the diameter by 2 to find the radius, but with the 9 pi, it makes me unsure if I'm doing this correctly. ​

I need help please and thank you I know that you have to multiply the diameter by 2 to find the radius but with the 9 pi it makes me unsure if Im doing this cor class=

Respuesta :

tonb

Answer:

r=6

Step-by-step explanation:

The area of a circle is given by πr². Note that this uses the radius, not the diameter.

Now, one quarter of this area (ABC) is given to be 9π.

So apparently:

[tex]\frac14 \pi r^2 = 9\pi[/tex]

If you solve this:

[tex]\frac14 r^2 = 9[/tex] (divide both sides by π)

[tex]r^2 = 9\cdot4[/tex] (multiply both sides by 4)

so

r = √36 = 6

so the radius is 6.

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