8 4 6 4 3 2 5 10 Perimeter of KLMN 4 + 3 + 5 + 2 14 1 = = Perimeter of PQRS 8 + 6 + 10 + 4 28 2 4 1 5 1 8 2 10 2 3 1 2 1 4 6 2 2

Find perimeters of similar figures Example 5: A larger cement court is being poured for a basketball hoop in place of a smaller one. The court will be 20 feet wide and 25 feet long. The old court was similar in shape, but only 16 feet wide. a. Find the scale factor of the new court to the old court. b. Find the perimeters of the new court and the old court.

Example 6: ∆ WXY ~ ∆ PQR. Find the perimeter of ∆ WXY.

Example 7: In the diagram, ∆FGH ~ ∆JGK. Find the length of the altitude .

6.4 – Prove Triangles Similar by AA Goal: You will use the AA Similarity Postulate.

Use the AA Similarity Postulate Example 1: Determine whether the triangles are similar. If they are, write a similarity statement. Explain your reasoning.

Show that triangles are similar Example 2: a. b. ∆SVR and ∆UVT

Indirect Measurement: a way to measure something that is out of your reach by creating triangles for it and something you know the measurement of, thus creating ___________ triangles to make proportions. similar

Example 3: You stand in the shadow of a tree, so that you are 20 yards from the tree and your shadow is 16 feet long. If you stand 6 feet tall, how tall is the tree? (Draw a picture!)

Example 4: a) A lifeguard is standing beside the lifeguard chair on a beach. The lifeguard is 6 feet 4 inches tall and casts a shadow that is 48 inches long. The chair casts a shadow that is 6 feet long. How tall is the chair? b) In the above example, how long is the shadow of a person that is 4 feet 9 inches tall?