A circle has center (6, 2) and radius 9. Find all values of such that (x, - 1) is a point on the circle.

Question

A circle has center (6, 2) and radius 9. Find all values of such that (x, - 1) is a point on the circle.

Answer 1

the circle's equation is (x-6)^2 + (y-2)^2 = 81

if y=-1 then the equation becomes (x-6)^2 + 9 = 81

(x-6)^2 = 81-9 = 72

x-6 = sqr72 = + or - 6sqr2

x = 6 + or - 6sqr2