Analytic Geometry
posted by Lance .
What are the equations of the circles tangent to the xaxis, 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 + (y4)^2 = 16
you try the other circle with centre (2,4)