Angles  
Summary 
an angle is formed when two lines intersect at a point called the vertex. problems with angles often involve triangles, other polygons, parallel lines and circles. 
Key Skills 

Vocabulary 
vertex, degree, minute, complementary angles, supplementary angles, adjacent angles, acute angle, right angle, obtuse angle, reflex angle, congruent, vertically opposite, transversal, corresponding angles, alternate angles, cointerior angles. 