Looking at the above image what geometric figure can be constructed with our given lines that may help us. Remember we are trying to determine at what point the lines will intersect, so we can create the center of our tangent circle. The clearest geometric figure that we can construct will be a triangle. However, our goal is to create a length that is equal to the radius of c2 and the radius of the tangent circle.
What triangle has any sides that are equal?