Similarity of Triangles by Angles

The Angle-Angle Similarity (AA ~) Theorem states if two angles of one triangle are _______________ to two angles of another triangle, then the triangles are ____________________.

• adjacent; equal

• complementary; scalene

• congruent; similar

• supplementary; isosceles

Are the triangles similar?

• Yes

• No

Determine whether the triangles are similar(name the postulate or theorem you used).

• SSS similar

• AA similar

• SAS similar

Determine whether the triangles are similar or not. If so, state how they are similar.

• Yes, by AA Similarity

• Yes, by SAS Similarity

• Yes, by SSS Similarity

• No, not similar

Are these triangles similar?
Known angles in Triangle 1:  40⁰,60⁰
Known angles in Triangle 2:  60⁰,40⁰

• Yes

• No

• There is not enough information to decide.

2 triangles are similar if _____________.

• their angles are congruent.

• their sides are congruent.

• their areas are equal.

• their perimeters are equal.

Complete each proportion.
CB / DM  =  AC / ?

• BM

• MA

• BC

• AD

Complete each proportion.
AB / BM  =  ? / CD

• BC

• AC

• MD

• MC

Complete the similarity statement.
ABC ~ ___

• ZYX

• XZY

• YZX

• XYZ

How many pairs of congruent angles in 2 triangles are needed to prove the 2 triangles are similar?

• 2 or 3

• 1

• 0

• only 3