BASIC GEOMETRY Section 7.3: Triangle Similarity: AA, SSS, & SAS

Proving Triangles are Similar AA ~ Thm: If two angles of one triangle are congruent to two angles in another triangle, then the triangles are similar.

SSS ~ Thm: If the 3 sides of one triangle are proportional to 3 sides of another triangle, then the triangles are ~.

SAS ~ Thm: If two sides of one triangle are proportional to two sides of another and the included angles are congruent, then the triangles are ~.

Proofs These 3 Thms are used the same as the congruent triangles ones in proofs. Properties of Similarity

Example 1: Explain why the triangles are similar and write a similarity statement.

Example 2: Verify that the triangles are similar. A) ∆PQR & ∆STU B) ∆DEF & ∆HJK

Example 3: Explain why ∆ABE ∼ ∆ACD, and then find CD.

Example 4: The photo shows a gable roof. AC // FG Example 4: The photo shows a gable roof. AC // FG. Find BA to the nearest tenth.

Assignment #3 Page 474 #’s 1-6,9,10,34-36,(44)