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Question 656311: given A (3,-2) and B (-4,-1) find slope intercept of the line perpendicular to AB through A
Answer by chandrak(4)   (Show Source):
You can put this solution on YOUR website! A (3,-2)= (x1,y1)
B (-4,-1)=(x2,y2)
If Equation of a line is
y = mx + c1
then the equation of perpendicular line will be
y = (-1/m)x + c2
So if you find the slope of the first line we get the slope of the perpendicular line
slope = (y2-y1)/(x2-x1)
y2-y1 = -1-(-2) = 1
x2-x1 = -4-3 = -7
slope m = (y2-y1)/(x2-x1) = -1/7
so the slope of perpendicular line is -1/m = -1/(-1/7) = 7
perpendicular line equation is y = 7x + c2
to find intercept substitute point A since line passes through A
-2 = 7 * 3 + c2
c2 = -2 -21 = -23
slope = 7
y intercept = -23
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