# Geo4.74

From Example Problems

Find the condition that the two circles and touch eachother.

Let the equations of the two circles are

There is no constant term in both the equations. So both the circles touch each other at O(0,0).

Centre of the circles are

The circles touch eachother. A,O,B are collinear

Hence Slope of AO=Slope of BO

This is the required condition.