if , , , and . Is a rhombus? Show how you know.
Compare the lengths of all four sides.
Find the equations of the lines on which the diagonals lie. That is, find the equations of
Find the slopes and the
-intercepts of the lines and write the equations of the lines in slope-intercept form ( ).
Equation for line
Compare the slopes of
and . What do you notice?
What do you know about the slopes of parallel and perpendicular lines?