Respuesta :

[tex]a = \pi \: {r}^{2} [/tex]

u take ur known variables and fill them in, pi will be filled in as 3.14

Example:

[tex]153.86 = 3.14 {r}^{2} [/tex]

Then divide both sides by 3.14, after that it should be (number) =r². since it's squared you have to find to square root of both.

Example:

[tex] \sqrt{49} = \sqrt{ {r}^{2} } \\ 7 = r[/tex]

therefore in this example the radius is 7

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