1. Similar Triangles and Indirect Measurement
Lesson #5
Pg. 139

2. Vocabulary Indirect Measurement (Draw picture)
A techniques using properties of similar polygons to find distances or lengths that are difficult to measure directly.
Examples
A single bacteria, height of a roller coaster, diameter of the moon, etc.

3. Angle-Angle (AA) Similarity
If two angles of one triangle are congruent to two angles of another triangle, then the triangles are similar C B A F H G

4. Example Determine whether the triangles are similar.
If so, write a similarity statement
62°
70° B A C
62°
48° E G F

5. Example Determine whether the triangles are similar.
If so, write a similarity statement L
110° H M K J

6. Use Indirect Measurement Example
A fire hydrant 2.5 feet high casts a 5-foot shadow. How tall is a street light that casts a 26-foot shadow at the same time?
We have similar triangles
Let h represent the height of the street light
Remember to go across figures
Shadow Height

7. Example
In the figure at the right, triangle DBA is similar to triangle ECA. Ramon wants to know the distance across the lake C
162 m B
d m
320 m
40 m A D E

8. Homework All Classes: pg. 143-144 (1-9, 11-12) Test Tuesday www. ixl
Homework All Classes: pg (1-9, 11-12)   Test Tuesday   H9