SOLUTION: What is the slope of a line that is perpendicular to the line that passes through the points (4,7) and (9,3)? (can you include some steps to finding this answer?)

Algebra ->  Linear-equations -> SOLUTION: What is the slope of a line that is perpendicular to the line that passes through the points (4,7) and (9,3)? (can you include some steps to finding this answer?)      Log On


   

Question 50481: What is the slope of a line that is perpendicular to the line that passes through the points (4,7) and (9,3)?


(can you include some steps to finding this answer?)
Answer by adamchapman(301) About Me  (Show Source):
You can put this solution on YOUR website!
The gradient of the line between the two points given is found using the formula:
m=%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29
where 'm' is the gradient of the line, and:
(x1,y1)=(4,7)
(x2,y2)=(9,3).
now plug those values into the formula I just gave you:
m=%283-7%29%2F%289-4%29
m=-2%2F5
So the gradient of that line is -2/5.
All you need to do to find the gradient of a line perpendicular to another is divide minus one by the known gradient. Tis is easier to explain with another formula. Let 'p' be the gradient of the line perpendicular to the line with gradient 'm':
p=-1%2Fm
Its that simple!
Lets put in the value of 'm' that we found earlier:
p=-1%2F%28-2%2F5%29
p=5%2F2
You might notice that if 'm' is a fraction, all you need to do to find 'p' is turn the fraction upside-down and change its sign.
I hope this helps. I also run a tuition website of my own. Check it out at www.geocities.com/quibowibbler
Adam