equation of the circle

Question

Put the equation of the circle in standard form, identify the center (h,k) radius r of the circle.

x²+y²-2x-12y+28=0

Answer 1

You simply complete the square.

x² + y² - 2x - 12y + 28 = 0

x² - 2x + 1 - 1 + y² - 12y + 36 - 36 + 28 = 0

(x - 1)² + (y - 6)² = 1 + 36 - 28

(x - 1)² + (y - 6)² = 9

The center is (1, 6) and the radius is 3