Aa similarity
MathDefinition
A postulate stating that if two angles of one triangle are congruent to two angles of another triangle, then the triangles are similar. Since the angles of a triangle always sum to 180°, matching two angles guarantees the third also matches.
Examples
- Two triangles both have angles of 50° and 60°, so by AA similarity their sides are proportional
- A flagpole and a person both cast shadows on level ground, forming similar triangles by AA that let you calculate the flagpole's height
Key Fact
Two pairs of congruent angles → triangles are similar
Study This Concept
Practice AA similarity with free review games in these units: