Question 726068
The line x+3y-2=0 bisects the angle between the pair of straight lines of which one has the equation x-7y+5=0. The equation of other line 
------------------
Find the point of intersection of the 2 lines and the slope of each line.
x+3y-2=0 slope = -1/3 (the bisector line)
x-7y+5=0 slope = 1/7
--> (-1/10,7/10) intersection
-----------
The angle between the lines and the x-axis is the atan of the slope.
atan(-1/3) =~ -18.435 degs
atan(1/7) =~ 8.13 degs
---------------
The angle between the 2 lines =~ 26.565 degs
The angle of the "other line" will be -26.565 -18.435 = -45 degs
Its slope = -1 and it passes thru (-1/0,7/10)
-------
--> y = -x + 6/10