A line segment is bisected by a line with the equation # -6 y - x = 3 #. If one end of the line segment is at #( 5 , 1 )#, where is the other end?

2 Answers
Nov 23, 2017

Coordinates of the other end are #(167/37), -(84/37)#

Explanation:

Assumption : The line bisecting the segment is its perpendicular bisector.

Eqn of line # x + 6y = -3# Eqn (1)
#6y = -x -3#
#y = -(x/6) - (1/2)#
Slope of the line is -(1/6)#

Slope of altitude the line segment is 6
Eqn of line segment is
#y -1 = 6 (x-5)#
#y - 6x = 1-30 = -29# Eqn (2)
Solving Eqns (1) & (2) we get the intersection of the lines or the midpoint of the line segment.
Coordinates of mid point are #(171/37), -(47/37)#

#171/37 = (5+x_2)/2, -(47/37) = (1+y_2)/2# where #x_2, y_2 #are the coordinates of the other end point.

#x_2 = (342/37) -5 = 167/37#
#y_2 = -(47/37)-1 = -(84/37)#

Nov 23, 2017

#(157/37 , -131/37 )#

Explanation:

First we need to find the equation of the line that is perpendicular to the line #-6y-x=3# and passes through the point #( 5 , 1 )#. Since these lines are perpendicular we can find the gradient of the required line by using the fact that, if #m_1#is the gradient of the known equation, then #m_1*m_2=-1#

#:.#

#-1/6*m_2=-1=>m_2=6#

So second equation is:

#y-1=6(x-5)=>y=6x-29#

The point of intersection of these lines is the coordinates of the midpoint of the line segment.

Solving simultaneously:

#-1/6x-1/2=6x-29=>x=171/37#

#y=6(171/37)-29=-47/37#

We know for a line segment with coordinates #( x_1 , y_2)# and #( 5 , 1 )#, that the coordinates of the midpoint are #((5+x_1)/2 , (1+y_1)/2)#.

Midpoint coordinates:

#(171/37 , -47/37 )#

#:.#

#(5+x_1)/2=171/37=>x_1 =157/37#

#(1+y_1)/2=-47/37=>y_1=-131/37#

Coordinates of end point of line segment:

#(157/37 , -131/37 )#

Plot:

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