10.1 Use Properties of Tangents

•  Circle:  Set  of  all  points  in  a  plane  that  are  equidistant  from  the  center  

•  Radius:  segment  whose  endpoints  are  the  center  and  any  point  on  the  circle  

•  Chord:  segment  whose  endpoints  are  on  a  circle  

•  Diameter:  Chord  that  contains  the  center  of  the  circle  

•  Secant:  Line  that  intersects  the  circle  in  two  points  

•  Tangent:  Line  or  ray  that  intersects  the  circle  at  exactly  one  point  

•  Point  of  Tangency:  Exact  point  where  tangent  intersects  the  circle  

Coplanar  Circles  Two  circles  intersecting  in  two  points,  one  points,  or  no  points    

**Sharing  a  common  center  

Common  Tangents  Line,  ray,  or  segment  that  is  tangent  to  two  coplanar  circles  is  

called  a  common  tangent  

Hwk  p.  655  (3-­‐10,  all,  15-­‐25,  odd)