Question

A circle has its center at (-1, 2) and a radius of 3 units. What is the equation of the circle?

(x - 1)2 + (y + 2)2 = 3

(x + 1)2 + (y - 2)2 = 3

(x + 1)2 + (y + 2)2 = 9

(x + 1)2 + (y - 2)2 = 9

Answer 1

@BritBratt13

Answer 2

(x-h)^2 + (y-k) ^2 = r^2 Standard equation of a circle

Answer 3

When the center of the circle is at (0,0), and the radius is r, the standard equation is\[x^2+y^2=r^2\]and when the center is at (h,k), the equation is\[(x-h)^2+(y-k)^2 = r^2\]

Answer 4

Please apply the appropriate formula to answering your posted question.

Answer 5

I don't know what I am doing

Answer 6

You're given the center of the circle. What is it? See the original problem statement.

Answer 7

(-1,2

Answer 8

OK: That point is your (h,k). the x-coordinate of the center is x=-1, and the x-coordinate is ... ???

Answer 9

-1

Answer 10

That's right: h=-1. Next, k=?

Answer 11

K=2

Answer 12

Good. Now, taking the standard form of the equation of a circle centered at (h,k), and substituting (-1) for h and substituting (2) for k, what do you get?\[(x-h)^2+(y-k)^2 = r^2\]

Answer 13

(X-(-1))^2+(y-2)^2=3^2

Answer 14

Yes. Please simplify that. x-(-1)=? and so on.

Answer 15

(X+1)^2+(y-2)=9

Answer 16

Looks great. Any questions about the procedures we've used here?

Answer 17

No thanks for the help

Answer 18

Thank you for the medal. Hope to work with you again soon.