A circle in the coordinate plane is tangent to the y-axis at the point (0,5) and passes through the point (12,0). Find the radius of the circle.
Since the circle is tangent at (0,5) the center is (a,5)
The distance from this point to the gfiven points is equal.....so we can solve the simplified distance^2 formula for a
a^2 = (12 -a)^2 + ( 5)^2 simplify
a^2 = a^2 - 24a + 144 + 25
24a = 169
a = 169/24 = the radius
See the graph here : https://www.desmos.com/calculator/tm67fzywd1