Question 133222
Given points at (2,2), (4,3) (5,1) (3,0)
Are the lines that connect these points parallel and perpendicular? How doe sone know if one line is perpendicular to another? What does that say about their slopes?

segment from (4,3) to (2,2). slope is {{{(3-1)/(4-2)}}} = {{{1/2}}}
segment from (3,0) to (5,1). slope is {{{(1-0)/(5-3)}}} = {{{1/2}}} So these two segments are parallel since they have the same slope

segment from (4,3) to (5,1). slope is {{{(3-1)/(4-5)}}} = {{{-2}}} 
segment from (2,2) to (3,0). slope is {{{(2-0)/(2-3)}}} = {{{-2}}} these two are parallel since hey have the same slope

The slopes of the first set are the negative reciprocal of the second, so these lines are perpendicular.

The walls are perpendicular!