help stating postulate

Question

I have a shape that is an uneven rectangle:

 

                  D________________C

 

 

                A_______________B

 

D is 95 degrees, C is 80 degrees, A is 85 degrees and B is 100 degrees.

 

I need help stating which lines, segments or rays are parallel in this shape and stating the postulate or theorem which proves them parallel.

 

:)

Answer 1

Look at the obtuse ** angles formed by the intersection of BC with the 2 horizontal lines.  The obtuse angle at point C is 180 - 80 = 100 degrees

 

Since the obtuse angles at B and C are the same, we know that  AB and CD are parallel.

 

The same test fails at A and B, therefore AD and BC are NOT parallel

 

 

** You could also compare the 2 ACUTE angles