Section 8-3 Similar Triangles GEOMETRY

ENTRY TASK – TWO LEVELS Medium/Difficult F

Homework Review

Short Cuts for Similar Triangles AA ASA SSS

AA Similarity Postulate If two angles of one triangle are congruent to two angles of a second triangle, then the triangles are similar. This means that corresponding angles are congruent and corresponding sides are proportional!

SAS Similarity Theorem If an angle of one triangle is congruent to an angle of a second triangle, and the sides that include the two angles are proportional, then the triangles are similar. This means that corresponding angles are congruent and corresponding sides are proportional!

SSS Similarity Theorem If the corresponding sides of two triangles are proportional, then the triangles are similar. This means that corresponding angles are congruent and corresponding sides are proportional!

Example 1 Explain why the triangles are similar and write a similarity statement. Then find DE

Example 2 In the sunny desert a cactus casts a 9 foot shadow. At the same time a 6 foot tall person, standing next to the cactus, casts a 4 foot shadow. How tall is the cactus?

Example 3 Explain why the triangles are similar and write a similarity statement. Then find the value of x. 9 6

Example 4 A photograph measuring four inches wide and five inches long is enlarged to make a wall mural. If the mural is 120 inches wide, how long is the mural?

Example 4 – Proofs Using Triangle Similarity

Example 5 – Proofs Using Triangle Similarity

Homework Page 455 Problems: 7-13, 19, 23, 26