Question

What is the radius of the circle given by the equation below? x2 - 2x + y2 - 2y - 98 = 0?

Answer 1

Complete the square for the given equation
x² - 2x + ____ + y² - 2y + _____ = 98
x² - 2x + (1) + y² - 2y + (1) = 98 + (1) + (1)
(x - 1)² + (x - 1)² = 100
(x - 1)² + (x - 1)² = 10²

Now the equation is in the form (x - h)² + (y - k)² = r²

Radius = 10