Question

quick question about the equation of a circle, please help!

Answer 1

i know that the equation of a circle is \[(x - h)^{2} + (y - k)^{2} = r^{2}\]

but how what do i do when i get a question like Write the equation of a circle with a center of (0, 0) and a diameter of 20.

what do i do with the diameter?

Answer 2

put r=20/2=10

Answer 3

and then do i do 10^2 ?

Answer 4

yeah

Answer 5

\[d = 2r\]