SOLUTION: Given: x^2+y^2-6x+8y-11=0. 1. Find the equation of the circle in standard form. 2. Find the center and the radius.

Algebra ->  Circles -> SOLUTION: Given: x^2+y^2-6x+8y-11=0. 1. Find the equation of the circle in standard form. 2. Find the center and the radius.      Log On


   



Question 1171456: Given: x^2+y^2-6x+8y-11=0.
1. Find the equation of the circle in standard form.
2. Find the center and the radius.

Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
regroup the terms to get:
(x^2 - 6x) + (y^2 + 8y) - 11 = 0
complete the squares to get:
(x-3)^2 - 9 + (y+4)^2 - 16 - 11 = 0
combine like terms to get:
(x-3)^2 + (y+4)^2 -36 = 0
add 36 to both sides of the equation to get:
(x-3)^2 + (y+4)^2 = 36
that's your equation in standard form of a circle.
the center is at (3,-4) and the radius is equal to sqrt(36) = 6
here's the graph of both equations.



since they are identical, they make the same figure on the graph.