Download Postulate 4-1

4-2 Triangle Congruence using SSS and SAS
Postulate 4-1
Side-Side-Side (SSS) Postulate
If the three sides of one triangle are congruent to the three sides of another triangle,
then the two triangles are congruent.
A
D
DFG
ABC
C
B
G
F
Postulate 4-2
Side-Angle-Side (SAS) Postulate
If two sides and the included angle of one triangle are congruent to two sides and the
included angle of another triangle, then the two triangles are congruent.
D
A
C
B
1. In
G
F
ABP , which sides include
B
?
A
Segment AB and segment BP
2. In
DFG
ABC
P
YXP which angle is between PX and XY ?
Y
B
X
angle x and list it three different ways
3. Which triangles can you prove congruent?
Tell whether you would use SSS or ASA Postulate.
Vertical angles congruent (list them)  SAS  congruent statement
segment AB is congruent to segment XY  SSS  congruent statement
D
(there should be congruent marks on the figure sorry…)
4. What other information do you need to prove DWO  DWG ?
Prove using SSS and SAS
O
5. Can you prove
SSA , NO
SED  BUT
from the information given? Explain.
W
G
Sample Proofs for 4-2 (SSS and SAS)
Given:
Prove:
AB DE , AB  DE , BC  FE
∆ABF  ∆DEC
B
A
D
C
F
E
B
Given:
Prove:
ABC is isosceles with base AC
D is the midpoint of AC
ABD  CBD
A
D
C