Question

1. Prove that the opposite sides of a parallelogram
are equal in length.
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Answer 1

Step-by-step explanation:

$In \: triangle \: ADC \: and \: ABC \: \\ DAC=∠ACB \: ( \: AB \: ∥ \: CD and \: taking \: AC \: as \: transversal \: ) \\ AC=AC  \: ( \: common \: ) \\ DCA=∠BAC( \: AB \: ∥ \: CD \:  taking \: AC \: as \: transversal \: ) \\ By \: ASA \: criterion \: of \: concurrency \: triangle \: ADC \: is \: congruent \: to \: triangle \: ABC. \\ AD=BC ( \: By \: CPCT \: )  \\ AB=CD ( \: By \: CPCT \: )$