Posted by Bridget on .
Find the slope of the lines that are (a) parallel lines (b) perpendicular lines to the lines passing through the pair of points (3, 4)(2,1)

math 
Kuai,
y2y1 /x2x1
14/ 23
m = 5/1
m = 5
parallel = slope 5
perpendicular slope 1/5 
math 
Reiny,
slope with the given points
= (14)/23) = 5/1 = 5
so any parallel line has slope 5
any perpendicular line has slope 1/5 
math 
Jai,
To get the slope we use the formula:
m = (y2  y1) / (x2  x1)
where (x1,y1) and (x2,y2) are the points.
Substituting,
m = (4  (1)) / (3  2)
m = (4 + 1) / 1
m = 5
(a) Note that parallel lines have equal slope. Thus slope of the parallel line is also equal to 5.
(b) Note that perpendicular lines have negative reciprocal of slope of each other. Thus, the slope of perpendicular line is equal to 1/5.
Hope this helps :3