1 method of solving these type of problems :
Given straight lines : y + 2x = 3 and y + 2x - 5 = 0
They pass through the point , (2,3)
r = - [ ax1 + by1 + c / (acos
+ b sin
]
where (x1 , y1) = 2,3
Hence r = - [ 2(2) + 1(3) - 3 / 2 cos
+ sin
] = - ( 4 / 2 cos
+ sin
)
Now its given that it makes an intercept of length 2 units , hence
r+2 = - [ 2(2) + 1(3) - 5 / 2 cos
+ sin
] = - ( 2 / 2 cos
+ sin
)
Hence subtracting the two we get ,
r+2 - r = 2 = 2 / (2cos
+ sin
)
Hence 2 cos
+ sin
= 1
or 4 cos 2
= ( 1 - sin
) 2
So 4(1 - sin
) (1 + sin
) - (1 - sin
) 2 = 0
or (1 - sin
) [ 4 (1 + sin
) - [ 1 - sin
] = 0
Hence sin
= - 3/5
Thus cos
= 4/5
or sin
= 1 and cos
= 0
So two cases are ,
1.) x-2 / 4/5 = y-3 / (-3/5)
Hence , -3(x-2) = 4(y - 3)
or 4y + 3x = 18
2.) x-2/ 0 = y-3/1
or x-2/y-3 = 0
Hence x-2 = 0
Thus the 2 equations are ,
x = 2 and 4y + 3x = 18 ................ans 