Answer:
B. CPCTC
D. opposite sides are congruent
Explanation:
You want to know the necessary claims for proving opposite angles are congruent in a parallelogram.
Proof
Given parallelogram ABCD and diagonal AC, you can prove opposite angles congruent in this way:
AB≅CD and BC≅DA . . . . . opposite sides are congruent
AC≅CA . . . . . . . . . . . . . . reflexive property of congruence
∆ABC≅∆CDA . . . . . . . . . . . SSS congruence
∠B ≅ ∠D . . . . . . . . . . . . Corresponding parts of congruent triangles
When doing the proof, the necessary claims are ...
B. Corresponding parts of congruent triangles are congruent
D. Opposite sides are congruent.
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