SOLUTION: GIVEN: ABCDEF is a regular hexagon PROVE: triangle ABC congruent to triangle BCD

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         statement                          reason
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1. ABCDEF is a regular hexagon            1.Given

2. AB congruent DC                        2.def. of reg hexagon

3. BC congruent BC                        3.relexive prop

4. angle ABC congruent angle BCD          4. def. of reg hexagon

5ABC congruent to BCD               5. SAS



SAS-if two sides and the included angle of one  are congruent
    to the corresponding parts of another  the 's are 
    congruent.