Given:
ABCD is a parallelogram.
To prove:
[tex]AD\cong BC\text{ and AB}\cong CD[/tex]
Proof:
[tex]\begin{gathered} \text{ABCD is a parallelogram}\ldots\ldots\text{ given.} \\ DC\parallel AB\text{ and AD}\parallel BC\ldots\ldots..by\text{ definition of parallelogram} \\ \angle\text{DCA congruent to }\angle\text{BAC; }\angle BCA\text{ congruent to }\angle DAC\ldots\ldots\text{.}AI\text{ angles theorem} \\ AC\cong AC\ldots.\text{ reflexive property} \\ \Delta ADC\cong\Delta CBA\ldots.by\text{ ASA} \\ AD\cong BC\text{ and AB}\cong CD\ldots\ldots by\text{ CPCTC} \end{gathered}[/tex]
Hence proved.
