The proof is shown below:
What is a parallelogram?
A parallelogram is a quadrilateral with opposite sides parallel (and therefore opposite angles equal).
As,
<A= 104
<B= 76
As AB || CD,
<A + <D =180
104 + <D =180
<D = 76
and <B + <C =180
76 + <C = 180
<C = 104.
As, opposite angles are equals and AB || CD.
Hence, ABCD is a parallelogram.
For 2 part,
Use m<A = 104° and m<B= 76° to show that <A and <B are same-side interior angles. Then, use AB || CD to show that <A and <D are supplementary angles.
learn more about parallelogram here:
https://brainly.com/question/23488153
#SPJ1
