Tangent Circles


By: Brooke Norman



Given two circles and a point on one of the circles, construct a circle tangent to the two circles with one point of tangency being the designated point.



Start out with a large circle of any size, label the center A. Then construct a smaller circle inside this large circle, label the center B.



Next place an arbitrary point on each circle and label them C and D.




Construct a line segment from B to C.  This will be used for the radius of a circle with center D.  Also, create a line that goes through points A and D.



Now, we are going to use line segment BC to create a like circle with center, D.




We will now label a point, E, that lies on the new circle and also on the new line.


We will now draw a line from point B to point E and label its midpoint. 




Next we will draw a line perpendicular to line BE and going through the midpoint F.




The last step is to create a circle with a radius the length of GD.  This creates our circle that is tangent to two other circles.




If we hide all of our tools for construction, we should be left with a picture that looks like: 




If you would like to play around with tangent lines, use the following link to go to a script tool for tangent circles.



Return to EMAT 6680 Class Page for Brooke Norman.