# perpendicular

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• Feb 26th 2008, 04:35 PM
dude
perpendicular
is y = 4-x Perpendicular to y = 6+x

y=-1x+4 recip y=1x+6

True Or False?
• Feb 26th 2008, 09:00 PM
heathrowjohnny
1. true

2. dont understand question
• Feb 26th 2008, 09:59 PM
Mathnasium
A little extra on #1:

Put both equations into slope-intercept form, so they look like y = mx + b. Remember than in slope-intercept form, "m" represents the slope of the line.

So, your two equations become:

y = -x + 4

and

y = x + 6.

Thus, the slopes of your two lines are -1 and 1, respectively. (Remember that x really means 1x, and -x really means -1x.)

Now, two lines are perpendicular if and only if their slopes are negative reciprocals of one another. Consider the slope of 1 (the slope of your second line). Think about it as 1/1 (any whole number can be written as a fraction simply by putting it over 1). Now, take the 1/1 slope, make it negative and flip it over. This gives you -1/1, which is the same as -1, which is the slope of your first line. So the slopes of the two lines are negative reciprocals of one another and the lines are therefore perpendicular.

As for #2, maybe you're just restating #1, in which case I think the explanation above should answer your question.