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.

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- Sep 8th 2008, 01:28 PM~berserkSlope 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 PMMatt Westwood
Let line L have a gradient of G. Then a line perpendicular to L has gradient $\displaystyle \frac {-1}{G}$.

Does that help? - Sep 8th 2008, 01:36 PM~berserk
not really...

- Sep 8th 2008, 02:08 PMMatt 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.