SOLUTION: find the value of Y so that the line through (-2,-1) and (10,y) is perpendicular to the line through (6,-2) and (5,7) Thanks

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Question 98831: find the value of Y so that the line through (-2,-1) and (10,y) is perpendicular to the line through (6,-2) and (5,7)
Thanks

Answer by malakumar_kos@yahoo.com(315) About Me  (Show Source):
You can put this solution on YOUR website!

find the value of Y so that the line through (-2,-1) and (10,y) is perpendicular to the line through (6,-2) and (5,7)
When two lines are perpendicular the product of their slopes =-1
slope of line through (-2,-1) and (10,y) = y-(-1)/10-(-2)
m = y+1/10+2
= (y+1)/12
slope of line through (6,-2) and (5,7) = (7-(-2))/5-6
M = 7+2/-1
= -9
m.M = -1
(y+1).(-9)/12 = -1
(y+1) = -1.12/-9
y+1 = 4/3
y = 4/3-1
= 4-3/3 = 1/3
value of y = 1/3