Question 973512
So I took a state test today and I'm not sure if I messed up or if I will get partial credit for my work, but here goes.
We had to prove a quadrilateral was a rectangle and I showed that all the adjacent slopes were negative reciprocal giving it all right angles. 
IS THAT ENOUGH?
Did I have to show it was a parallelogram first? 
<pre>I believe that you will get partial credit since you didn't quite prove that it's a rectangle. 
Proving that adjacent sides have slopes that are negative reciprocals of each other does prove that
the 4 angles are right angles. 
However, this is also the definition of a square. I believe that you should have gone one step further by 
proving two adjacent sides non-congruent, and opposite sides congruent. Thus, it would definitely be a rectangle.