Information about Similarity day 1 sss, sas, aa

Published on March 5, 2014

Author: jbianco9910

Source: slideshare.net

#3.19 Geo. Drill 3/5/14 • Given that the following two pentagons are similar, find x. 8 12 4 6 x 14 5 4 10

Geometry Drill •Can you list the 5 ways to prove triangles congruent

Objective • Students will use the similarity postulates to decide which triangles are similar and find unknowns.

Congruence vs. Similarity •Congruence implies that all angles and sides have equal measure whereas...

Congruence vs. Similarity •Similarity implies that only the angles are of equal measure and the sides are proportional

AA Similarity Postulate •Two triangles are similar if two pairs of corresponding angles are congruent

AA Similarity Postulate E B A C D F

SAS Similarity Postulate •Two triangles are similar if two pairs of corresponding sides are proportional and the included angles are congruent

SAS Similarity Postulate E B 12 8 A 4 C D 6 F

SSS Similarity Postulate •Two triangles are similar if all three pairs of corresponding sides are proportional.

SSS Similarity Postulate E B 9 13 A 7 C 21 27 D 39 F

Example 1 •∆APE ~ ∆DOG. If the perimeter of ∆APE is 12 and the perimeter of ∆DOG is 15 and OG=6, find the PE.

Example 2 Explain why ∆ABE ~ ∆ACD, and then find CD. Step 1 Prove triangles are similar. A A by Reflexive Property of , and B C since they are both right angles. Therefore ∆ABE ~ ∆ACD by AA ~.

Step 2 Find CD. Corr. sides are proportional. Seg. Add. Postulate. x(9) = 5(3 + 9) 9x = 60 60 20 x 9 3 Substitute x for CD, 5 for BE, 3 for CB, and 9 for BA. Cross Products Prop. Simplify. Divide both sides by 9.

Explain why ∆RSV ~ ∆RTU and then find RT. Step 1 Prove triangles are similar. It is given that S T. R R by Reflexive Property of . Therefore ∆RSV ~ ∆RTU by AA ~.

Check It Out! Example 3 Continued Step 2 Find RT. Corr. sides are proportional. Substitute RS for 10, 12 for TU, 8 for SV. RT(8) = 10(12) 8RT = 120 RT = 15 Cross Products Prop. Simplify. Divide both sides by 8.

Writing Proofs with Similar Triangles Given: 3UT = 5RT and 3VT = 5ST Prove: ∆UVT ~ ∆RST

Example 4 Continued Statements Reasons 1. 3UT = 5RT 1. Given 2. 2. Divide both sides by 3RT. 3. 3VT = 5ST 3. Given. 4. 4. Divide both sides by3ST. 5. RTS VTU 5. Vert. s Thm. 6. ∆UVT ~ ∆RST 6. SAS ~ Steps 2, 4, 5

Given: M is the midpoint of JK. N is the midpoint of KL, and P is the midpoint of JL. Prove: ∆JKL ~ ∆NPM

Statements Reasons 1. M is the mdpt. of JK, N is the mdpt. of KL, and P is the mdpt. of JL. 1. Given 2. 2. ∆ Midsegs. Thm 3. 4. ∆JKL ~ ∆NPM 3. Div. Prop. of =. 4. SSS ~

Example 5: Engineering Application The photo shows a gable roof. AC || FG. ∆ABC ~ ∆FBG. Find BA to the nearest tenth of a foot. From p. 473, BF 4.6 ft. BA = BF + FA 6.3 + 17 23.3 ft Therefore, BA = 23.3 ft.

Check It Out! Example 5 What if…? If AB = 4x, AC = 5x, and BF = 4, find FG. Corr. sides are proportional. Substitute given quantities. 4x(FG) = 4(5x) FG = 5 Cross Prod. Prop. Simplify.

Conclusion •Similarity •AA •SAS •SSS

Classwork/Homework •Page 474-475 #’s 110, 17,18, 23, 24, 44-46

Share Similarity day 1 sss, sas, aa. Embed ...

Read more

... Unit 5 Day 1 HW- Special Segments in Triangles ... Triangle Similarity - SSS, SAS, and AA 128-2.28 - Duration: ... +YouTube; Terms; Privacy;

Read more

Mountjoy Geometry Triangle Similarity SAS Lesson 8.2b ... This feature is not available right now. Please try again later.

Read more

Theorems and postulates that prove similar triangles. SSS, AA and SAS, ... AA, SAS, SSS. I. AA Theorem. When 2 ... Problem 1. Can you use one of ...

Read more

Similarity by SSS and SAS. Add to Library . ... At a certain time of day, ... Previous Similarity by AA.

Read more

7.3 Triangle Similarity AA, SSS, SAS.notebook 1 January 20, 2012 Jan 133:25 PM Triangle Similarity: AA, SSS, and SAS Objective:

Read more

SSS Congruence Criterion The SSS ... done with AA and SAS similarity criteria, you will 1. define ... AA, SAS and SSS similarity criteria ...

Read more

Similarity by SSS and SAS. Add to Library . Share to Groups. Add to FlexBook® Textbook ...

Read more

7.3 Showing Triangles are Similar: AA ... write a similarity statement. 1. 2. J 27 8 27 8 K L H G 65 8 80 8 35 8 80 8 T S L N R M H G F K J L 29 8 61 8 Are ...

Read more

## Add a comment