posted by Lance .
What are the equations of the circles tangent to the x-axis, of radius 4 and whose center is at (-2,y)
Please help, how do I solve this problem?
Since (-2,0) must be on the circle , (it is tangent to that point)
y must be either 4 or -4
first case: y = 4
centre is (-2,4) radius is 4
equation: (x+2)^2 + (y-4)^2 = 16
you try the other circle with centre (-2,-4)