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Question 110990:  can you show me how to find the distance between each pair of parallel lines  y=3x   and   y=3x + 10
 
 
 
 
 
 
 
 
 Answer by scott8148(6628)      (Show Source): 
You can  put this solution on YOUR website! he distance is the length of a perpendicular line drawn between the parallel lines
 
 
perpendicular means the slope will be -1/3 (negative reciprocal of 3) 
... 10 is the y-intercept of the upper line, so the perpendicular will match it 
... the perpendicular intersects the top line at (0,10)
 
 
the intersection with the bottom line is when 3x=(-1/3)x+10 ... or x=3 ... so the intersection is (3,9)
 
 
the distance is between the two intersections ... d^2=(3-0)^2+(9-10)^2 
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