# Slope Problem

• Sep 8th 2008, 01:28 PM
~berserk
Slope Problem
The line joining (3,h) and (5,10) is parallel to y=3x+4 Find h. I found h to be 4 which I know is correct. Secondly, find h if these two lines are perpendicular. This is the part I don't know how to do.
• Sep 8th 2008, 01:33 PM
Matt Westwood
Let line L have a gradient of G. Then a line perpendicular to L has gradient $\frac {-1}{G}$.

Does that help?
• Sep 8th 2008, 01:36 PM
~berserk
not really...
• Sep 8th 2008, 02:08 PM
Matt Westwood
You found h, presumably by making the gradient of the line joining (3,h) and (5,10) the same as the gradient of y=3x+4 (i.e. 3).

So now you want to select h so that the gradient of the line joining (3,h) and (5,10) is -1/3.