The formula for the area of a circle is A: [tex] \pi [/tex]r² If you plug in the numbers, you get 81[tex] \pi [/tex]: [tex] \pi [/tex](x)² If you divide the [tex] \pi [/tex] on either side, they cancel each other out, leaving 81: (x)² You will find the square root of 81, which is 9. Your radius is then 9.
The circumference formula is C: 2[tex] \pi [/tex]r If you plug the numbers in, you get C: 2[tex] \pi [/tex](9) You do the math and get the circumference, C: 18[tex] \pi [/tex] units²
