How do I find center of a circle?

Answer by  Madhavi (29)

Using a straightedge draw any two chords of the circle.Construct perpendicular bisector of one of chords. Repeat for other chord. Point where two lines intersect is the center of the circle.

Answer by  anrimala36 (208)

If you are given the formula, say x^2+2x+y^2-4y=4, you convert it into standard form, (x-h)^2+(y-k)^2=r^2, where (h,k) are the coordinates of the circle's center and r is the radius. To do this, you must complete the square: x^2+2x+_1_+y^2-4y+_4_=4+_1_+_4_ = (x+1)^2+(y-2)^2=9. The circle's center for this example is (-1,2).