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.

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 ABC @ D EDF

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

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

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

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

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

Construction – p. 228 Copy an angle p. 33

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