Question 978141:  the line y=2x+7 is parallel to the line y=2x-3.The line y= -0.5x+7 is perpendicular to the line y=2x-3. Find the perpendicular distance between the pair of parallel lines. 
 Answer by KMST(5328)      (Show Source): 
You can  put this solution on YOUR website! Line   is parallel to line   , 
which is perpendicular to   , 
so   and   are perpendicular to each other. 
So the distance between   and   
is the distance, along   , 
between the points where   intersects the other two lines. 
Lines   and   obviously intersect at point   , the y-intercept for both lines. 
We can find the point   where   and   intersect 
by solving   
I wanted to graph anyway, and in the graph it looked like it was   . 
Substituting   to see that   for both lines confirmed that solution: 
  and  
 
 
   
The distance from   and   
is the distance between   and   . 
The distance between two points can be calculated according to a formula: 
  , 
but there is no need (usually) to memorize formulas, 
if you understand their meaning. 
That distance is the hypotenuse of a right triangle, 
like the one in my drawing, 
whose legs, parallel to the x-axis and y-axis, 
are the horizontal distance and the vertical distance between the points. 
In this case, 
 (rounded). 
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