Find the equations of the lines through the point of intersection of the lines x – y + 1 = 0 and 2x – 3y + 5 = 0 and whose distance from the point (3, 2) is 7/5.
Given two lines are: x-y+1=0 and 2x-3y+5=0
Solving these two equations gives us points of intersection we get y=3 and x=2
(x,y)=(2,3)
Let m be the slope of the required line
Then, equation of the line is y-3=mx-2
y-3=mx-2m
mx-y-2m+3=0….(1)
Since, the perpendicular distance from the point 3,2to the line is75then
Squaring both the sides, we get
49m2+1=25(m+1)2
49m2+49=25m2+25+50m
25m2+25+50m-49m2-49=0
-24m2+50m-24=0
-12m2+25m-12=0
Factorising, we get (3m-4)(4m-3)=0
3m-4=0 or 4m-3=0
3m=4 or 4m=3
m=4/3 or 3/4
Putting the value of m=4/3 in equation 1 we get 4x/3-y-2(4/3)+3=0
4x/3-y-8/3+3=0
4x/3-y=-1/3
4x-3y+1=0
Putting the value of m=3/4 in the equation we get 3x/4-y-2(3/4)+3=0
3x/4-y-3/2+3=0
3x/4-y+3/2=0
3x-4y+6=0
Hence, the required equation are 4x-3y+1=0 and 3x-4y+6=0