Find the points on the line x + y = 4 which lie at a unit distance from the line 4x + 3y = 10.
Let x1, y1 be any point lying inthe equation x+y=4
x1+y1=4…......(1)
Distance of point x1,y1from the equation 4x+3y=10
4x1+3y1-10=±5
4x1+3y1-10=5 or 4x1+3y1-10=-5
4x1+3y1=(15)...….(2) or 4x1+3y1=5….....(3)
From equation 1 we have y1=4-x1….. (4)
Putting the values of y1in equation 2 we get 4x1+3(4-x1)=15
4x1+12-3x1=15
x1=15-12 =3
Putting the value of x1in equation 4 we get y1=1
Now, 4x1+34-x1=5
4x1+12-3x1=5
x1=5-12 x1=-7
Putting the value in equation 4 we get y1=4--7=4+7=11
Hence, the required points on the given line are (3,1) and (-7,11)