BITSAT 2017 Slot 2 Solved Paper

The third side is parallel to a bisector of the angle between equal sides.
The bisectors are 7x−y+3=±5(x+y−3)
⇒2x−6y+18=0
or 12x+4y−12=0
⇒x−3y+9=0
or 3x+y−3=0
Let the third side be x−3y=k or 3x+y=L
It passes through (1,−10).
k=31,L=−7
Hence, required lines are x−3y=31,3x+y=−7