Why is it necessary to check angle measures in nonrectangular parallelograms but not in rectangles?

Rectangular paralellagrams all have 90 degree angles, so it's unnecessary to check for them. In nonrectangular parallelograms,they may or may not have 90-degree angles.  

its 8

step-by-step explanation:

the answer is (-8,-5)

step-by-step explanation:

the endpoint to midpoint is half the length. the length is (-2,-1) so when you are at the midpoint just add it to it to find your answer -6+(-2)= -8 and -4+(-1)=-5 so (-8,-5)