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Geometry. 5.6 Proving Triangles Congruent using ASA and AAS. EQ: What other ways can you prove triangles congruent?. Goals. Use ASA and AAS postulates to prove two triangles are congruent. Solve problems using congruence postulates. AC is included between A and C.
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Geometry 5.6 Proving Triangles Congruent using ASA and AAS EQ: What other ways can you prove triangles congruent?
Goals • Use ASA and AAS postulates to prove two triangles are congruent. • Solve problems using congruence postulates. Geometry 5.6 Proving Triangles Congruent: ASA, AAS
AC is included between A and C. AB is included between A and B. CB is included between C and B. Included Sides C B A Geometry 5.6 Proving Triangles Congruent: ASA, AAS
C Z A B X Y Theorem 5.10: Angle-Side-Angle If two angles and the included side of one triangle are congruent to corresponding parts of another triangle, then the triangles are congruent. (ASA) ABC XYZ Geometry 5.6 Proving Triangles Congruent: ASA, AAS
DB DB (Ref.) ExampleProve ADB CBD C D Proof: ADB CBD (Given) ABD CDB (Given) ADB CBD (ASA) A S A B A Geometry 5.6 Proving Triangles Congruent: ASA, AAS
E B F C D A Theorem 5.11 Angle-Angle-Side • If two angles and a nonincluded side of one triangle are congruent to corresponding parts of another triangle, then the triangles are congruent. ABC DEF Geometry 5.6 Proving Triangles Congruent: ASA, AAS
A S B D C ExampleIs ABC ADC? Yes,by AAS A A Geometry 5.6 Proving Triangles Congruent: ASA, AAS
Are these triangles congruent? Yes. Reason: AAS OR AAS. Geometry 5.6 Proving Triangles Congruent: ASA, AAS
Are these triangles congruent? You could even use ASA. Geometry 5.6 Proving Triangles Congruent: ASA, AAS
C C B B D D D D A A A A Overlapping Triangles Geometry 5.6 Proving Triangles Congruent: ASA, AAS
Problem: Is ABD DCA? C B 85° 85° 15° 15° D A YES by AAS Geometry 5.6 Proving Triangles Congruent: ASA, AAS
B C 85° 85° 15° 15° A D Problem: Is ABD DCA? C B 85° 85° 15° 15° D A YES by AAS Geometry 5.6 Proving Triangles Congruent: ASA, AAS
Methods to show triangles congruent: • SSS • SAS • ASA • AAS When trying to determine if triangles are congruent, carefully study the given information, mark the triangles if necessary, then determine what pattern you have. Geometry 5.6 Proving Triangles Congruent: ASA, AAS
BC ST T Problem A S S A B S A C R A A What other congruence must be given to show that ABC RST using the AAS postulate? Geometry 5.6 Proving Triangles Congruent: ASA, AAS
BA SR T Alternate Solution Problem A S B S A A C R S A A What other congruence must be given to show that ABC RST using the AAS postulate? Geometry 5.6 Proving Triangles Congruent: ASA, AAS
AC RT T Problem A B S A S C A R A S A What other congruence must be given to show that ABC RST using the ASA postulate? Geometry 5.6 Proving Triangles Congruent: ASA, AAS
State the third congruence that must be given to prove the given triangles congruent using the indicated postulate or theorem. Geometry 5.6 Proving Triangles Congruent: ASA, AAS
B F D C A E 1. ASA Theorem. C F Geometry 5.6 Proving Triangles Congruent: ASA, AAS
D A E B C F 2. AAS Theorem. C F Geometry 5.6 Proving Triangles Congruent: ASA, AAS
B D C F A E CB FE 3. SSS Geometry 5.6 Proving Triangles Congruent: ASA, AAS
4. SAS Theorem. F E A D C B A D Geometry 5.6 Proving Triangles Congruent: ASA, AAS
Is it possible to prove that the triangles are congruent? If so, state the postulate or theorem you would use. Explain reasoning Geometry 5.6 Proving Triangles Congruent: ASA, AAS
W X Z 5. Yes AAS Geometry 5.6 Proving Triangles Congruent: ASA, AAS
6. C A Yes SAS D R Geometry 5.6 Proving Triangles Congruent: ASA, AAS
T S O L F 7. The only other thing we know for sure: SOT LOF (Vertical Angles) But this spells… SSA NOT CONGRUENT Geometry 5.6 Proving Triangles Congruent: ASA, AAS
1. LA || SN L S 3. LR NR R A N Given: LA || SN, LR NR Prove: LAR NSR 1. Given 2. L N 2. Alt. int s 3. Given 4. LRA NRS 4. Vert s 5. LAR NSR 5. ASA Geometry 5.6 Proving Triangles Congruent: ASA, AAS
List four ways to show triangles are congruent. • SSS • ASA • SAS • AAS List one way that won’t work. SSA Geometry 5.6 Proving Triangles Congruent: ASA, AAS
Important! • To show two triangles congruent, at least one side must be known. • Three angles (AAA) does not show congruence (but it is still useful). Geometry 5.6 Proving Triangles Congruent: ASA, AAS
Summarize Geometry 5.6 Proving Triangles Congruent: ASA, AAS