Instruction Active
Proving the Parallelogram Side Theorem
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Given: ABCD is a parallelogram,
Prove: ABCD and BC-DA
Angles Segments Triangles Statements Reasons
ZBAC
ZBCA
ZDAC
ZDCA
B
С
Statements
1. ABCD is a parallelogram
2. AB || CD
3. BC || DA
4. draw AC
Reasons
1. given
2. def. of parallelogram
3. def. of parallelogram
4. unique line postulate
D
alternate interior angles theorem
Think about the angles created by AC.