1. 4-4 Proving Congruence SSS, SAS
Page 225 Materials: Paper, Straightedge, Compass
Construct a triangle congruent to the given triangle in the textbook using sides.

2. SSS (side-side-side) postulate
If three sides of one triangle are congruent to three corresponding sides of another triangle, then the triangles are congruent. A D E F C B
D D EDF

3. In two triangles, segments DF  UV, FEVW, and DEUW
In two triangles, segments DF  UV, FEVW, and DEUW. Write a congruence statement for the two triangles.
Figure out what you want to name the first triangle.
DFE
Match up the second triangle in the same order.
DFE  U
DFE  UV
DFE  UVW
Now try p. 226 Check your Progress 1A & 1B

4. Example #2
Check Your Progress #2
Use the distance formula

5. Included angle- formed by two given sides
A is the included angle of sides AB and AC C B
B is the included angle of sides AB and BC
C is the included angle of sides CB and AC

6. SAS (side-angle-side) - If two sides and the included angle of one triangle are congruent to the corresponding side and included angle of another triangle, then the triangles are congruent. E B F A C D

7. Determine whether the triangles below are congruent
Determine whether the triangles below are congruent. If so, write a congruence statement and explain why they are congruent. If not, explain why not. Y R S T X Z
RST  YZX by SSS

8. Construction – p. 228
Copy an angle p. 33

9. Check Your Progress Page 228 #3 Page 229 #4A & #4B 4A: not possible
4B: SSS