Yes, you have to find the slope of the lines and see that
and
Question:
Show the points , , & are vertices of a parallelogram.
I don't what I'm suppose to find the prove that it's a parallelogram. Should I find the slope m of the lines? or should I find the distance between the points? and what does vertices mean?!
EDIT: This question is related to the lesson of Inclination and Slope of a line.