10 April 2011 Geometry 10 April 2011 Geometry

Homework Due TODAY- please checkDO investigation 1, page 377Do page 380: 1 – 6

Homework due FRIDAYpg. 591: 1-15 oddpg. 599: 2, 5, 10

2) WARM UP FIND Xx

4.5

1210

ObjectiveStudents will use similar triangle to solove applied problems.

Students will take notes, do an investigation and solve problems.

Need to take quiz today 3-3:45:P1: Rebecca, Joey, Lauren H, BryanP6: Zarifa, James, Skyler

Name ShortcutAA SimilarityConjecture

If 2 angles of one triangle are congruent to 2 angles of another triangle, then the triangles are similar

SSS SimilarityConjecture

If the 3 sides of one triangle are proportional to the 3 sides of another triangle, then the two triangles are similar

SAS Similarity Conjecture

If 2 sides of one triangle are proportional to 2 sides of another triangle and the included angles are congruent, then the triangles are similar

Summary

Similarity shortcuts for triangles, like congruence shortcuts, refer to congruence of angles, but unlike congruence shortcuts, the refer to proportionality of sides. SSS, AA (AAA) and SAS are similarity shortcuts, which imply AAS and ASA are also similarity shortcuts because they imply AA.

Are two figures similar?

Strategies:1)Color code corresponding angles and sides2)Re-sketch figures so corresponding parts are

oriented in the same directions3)Use shortcuts to determine similarity: AA, SSS, SAS

pg. 598- NOTESPhysics principal angle of reflection

incoming angle outgoing angle

Draw the two triangles. They are similar based on WHAT similarity shortcut? http://www.youtube.com/watch?v=Qr8exoX-uE0

does it matter how carefully I measure?

% error =

example-- I measure from my toe instead of a perpendicular height from my eyes…..

actual observedactual

60 56 4 0.0667 6.7%60 60

error

InvestigationSupplies– each group needs mirror, yardstick, tape measureYour job– use indirect measurement to Your job– use indirect measurement to determine the height of an object in the roomdetermine the height of an object in the room EVERY STUDENT needs to complete a write up

1. sketch with all measurements/ calculations 2. measurement of height using a direct method.3.Compute % error YOU HAVE 15 minutes to complete your work.

debrief

1. How can you use your knowledge of similarity to find the height of a tree in the park?

2. Why is it important to measure carefully?

3. Do pg. 599, 1, 3, 4 and 7