8.3 Common Tangents
A common tangent to two circles is a straight line that touches each of the circles at only one point.
1. Intersect at two points
(a) Circles of the same size
Number of common tangents |
Properties of common tangents |
Two common tangents:
AB and CD |
AC = BD
AB = CD
AB parallel to // OR parallel to // CD |
(b) Circles of different sizes
Number of common tangents |
Properties of common tangents |
Two common tangents:
ABE and CDE |
AB = CD
BE = DE
OA // RB
OC // RD |