12.4 Similar Triangles and Similar Figures

Recall the meaning of similar—the shape is the same but the size may be different

Def. Scale Factor—ratio of the corresponding side lengths of a figure.

Def. Similar Triangles--∆ABC ~ ∆DEF iff A is congruent to D, B is congruent to E, C is congruent to F and .

ANGLE/ANGLE PROPERTY

AA versus AAA?????? –we only need two angles to prove similarity—this is if two angles of one triangle are congruent respectively to two angles of a second triangle, then the triangles are similar.

Example

THEOREMS

look at theorems