Question

what is the diameter of this circle
(x+4)^2 + (y-9)^2=18

Answer 1

The equation of a circle with center at (h, k) and radius r is:
\( (x - h)^2 + (y - k)^2 = r^2 \)

What is \(r^2\) in your equation?

Answer 2

18

Answer 3

Right.
Now notice that
\(r^ 2 =18\), so what is r, the radius?

Answer 4

4.24

Answer 5

wow i feel dumb now lol

Answer 6

Don't feel dumb.
Since \(r^2 = 18\), then \(r = \sqrt{18} \).
You were asked for the diameter. the diameter is twice the radius, so
\(d = 2\sqrt{18} \)

Which can be simplified to:

\(d = 6\sqrt{2} \approx 8.49\)

Answer 7

thank you