Similarity and Proofs

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

Complete each proportion.
CB / DM  =  AC / ?

• BM
• MA
• BC
• AD

Complete each proportion.
AB / BM  =  ? / CD

• BC
• AC
• MD
• MC

What is the value of X and Y ?

• X=2.5 and Y=6.5
• X=6.5 and Y=2.5
• X=3 and Y=7
• X=2 and Y= 5

Complete the similarity statement.
ABC ~ ___

• ZYX
• XZY
• YZX
• XYZ

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.

Are these triangles similar?
Angles in Triangle 1:  40⁰,60⁰, and 80⁰
Angles in Triangle 2:  40⁰,50⁰, and 90⁰

• 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.

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