i am trying to a c++ program that will determine if two circles intersect each other. the input will be <x,y> coordinates for the center of each circle followed by the radius of each circle. the output will state whether the circles overlap, don't overlap or tangential(touch each other at one common point)

This is simple geometry that you could have worked out by playing with circles on a piece of paper. Programming is THINKING first and foremost.

Calculate the distance between the two central points (see Pythagoras' theorem).
If that distance is more than the sum of the two radii, they do not touch.
If that distance is exactly the sum of the two radii, they touch (tangential, as you said above).
If that distance is less than the sum of the two radii, they overlap.