Parallel Lines  
Summary 
lines, on the same plane, are parallel if they never meet and always remain the same distance apart. a line crossing parallel lines is called a transversal. three special types of angles involve parallel lines and a transversal:

Key Skills 
solve angle problems involving corresponding angles, alternate angles and cointerior angles. 
Vocabulary 
parallel, corresponding angles, alternate angles, cointerior angles,transversal, supplementary angles, complementary angles, symmetry 