lesson 4-2 triangle congruence by sss and sas · practice 4-2 triangle congruence by sss & sas...
TRANSCRIPT
LESSON 4-2
TRIANGLE CONGRUENCE
BY SSS AND SAS
Objective: Prove two triangles are congruent
using the SSS and SAS Postulates.
Key Concepts
SSS (Side-Side-Side) Postulate
If the three sides of one triangle are congruent to the three
sides of another triangle, then the two triangles are
congruent.
(NOTES…DNG page 75-76)
XY AY
MY
Reflexive Property of Congruence
SSS Postulate
(DNG page 75) Proving Triangles Congruent
Key Concepts
SAS (Side-Angle-Side) Postulate
If two sides and an included angle of one triangle are congruent
to two sides and an included angle of another triangle, then the
two triangles are congruent.
Vocabulary…
What other information do you need to prove ADC BCD by SAS?
Reflexive Property of Congruence
ADC BCD
SAS
From the information given, can you prove RSG RSH? Explain.
(DNG page 76)
Reflexive Property of Congruence
SAS
X
X
/// ///
Practice 4-2 Triangle Congruence by SSS & SAS
Decide whether you can use the SSS or SAS Postulate to prove the triangles congruent. If so, write
the congruence statement, and identify the postulate. If not, write not possible.
X
ADB ≅ CDB by SAS
not possible not possible
TUS ≅ XWV by SSS not possible DEC ≅ GHF by SAS
Practice 4-2 Triangle Congruence by SSS & SAS
Decide whether you can use the SSS or SAS Postulate to prove the triangles congruent. If so, write
the congruence statement, and identify the postulate. If not, write not possible.
MKL ≅ KMJ by SAS PRN ≅ PRQ by SSS
X
not possible
Draw a triangle. Label the vertices A, B, and C. B
A C
BCA
BCAB and
B and A
AC
Practice 4-2 Triangle Congruence by SSS & SAS
14. Developing Proof Supply the reasons in this proof.
Statements Reasons
1. 1.
2. 2.
3. 3.
Given
CAAC Reflexive Property of ≅
ABC ≅ CDA SAS Postulate
X
Practice 4-2 Triangle Congruence by SSS & SAS
15. Write a proof.
Statements Reasons
1. 1.
2. 2.
3. 3.
Given
DFE ≅ HFG Vertical s are ≅.
DFE ≅ HFG SAS Postulate
Do not forget to take your HOMEWORK assignment sheet!!!