1. 7-3: Proving Triangles are Similar
Rigor: 1) Prove 2 triangles are similar
2) Use similar triangles to solve indirect measurement problems
Relevance : Logic and proof, indirect measurement

2. 3 Triangle Similarity Criterion
(AA ~) – If 2 pairs of corresponding angles are congruent, the ∆s are ~.
(SSS ~) – If all corresponding sides are proportional, the ∆s are ~.
(SAS ~) – If 2 pairs of corresponding sides are proportional and the included angle pair is congruent, the ∆s are ~.

3. Dissecting Similarity Statements
Turn to core book page 298
Complete example 2 and the reflection problems on your own.
Be ready to discuss reflection questions in a few minutes

4. EX 1: Are the triangles similar? Justify your answer.

5. EX 2: Prove that the triangles are similar.
A) B)

6. EX 3:

7. Indirect Measurement: One of my favorite applications of Geometry!
One method of indirect measurement is using similarity proportions of triangles!
Used to calculate the height of pyramids & mountains, width of rivers, etc.
Ancient Greek philosopher Eratosthenes even used similar triangles to approximate the radius and circumference of the earth!
C = Syene, Egypt (now Aswan)
A = Alexandria

8. EX 4: What is the height of the cliff?

9. EX 5: Using Indirect Measurement
A birdbath 2ft 6in tall casts an 18in shadow in a garden at the same time an oak tree casts a 90ft shadow. How tall is the tree?

10. 7-3 Classwork
Workbook pg 301 and 302 ALL

11. Honors: 7-3 Assignments Secondary Assignment:
Primary Assignment: Due Tuesday
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Codes:
Period 2:
Period 4:
Period 6:
Secondary Assignment:
Textbook pg 486 – 487 #1 – 7,10, 19, 23, 24

12. Standard: 7-3 Assignments
Primary Assignment: Due
Website: join.quizizz.com
Codes:
Period 1:
Period 5:
Period 7:
Secondary Assignment:
Textbook pg 486 – 487 #1 – 7,10, 19