Friday, July 12, 2013

Internal Common Tangents - Unequal Radius

Draw the given circles with centres O and P and radii R1 and R2 respectively such that 
R1 > R2
  1. Draw a line joining the centres O and P.
  2. With centre O and radius equal to (R1 + R2 ), draw a circle.
  3. From P , draw a line PT tangent to this circle.
  4. Draw a line OT cutting the circle at A.
  5. Through P , draw a line PB parallel to OA , on the other side of OP and cutting the circle at B.
  6. Draw a line through A and B. This is the required tangent.
  7. Similarly , draw another internal tangent through C and D.

This is a Java Applet created using GeoGebra from - it looks like you don't have Java installed, please go to