Equation of line passing through the point P(1,2) which makes an angle 45° with the X-axis is (y−2)=m(x−1) and m=tanθ =tan45°=1 ∴ Equation is y−2=1(x−1) y−2=x−1 ⇒x−y+1=0 Point of intersection of lines x−y+1=0 and 3x+4y+5=0 is Q Then, for Q x−y+1=0,y=x+1 Pult it in 3x+4v+5=0 3x+4(x+1)+5=0 ⇒3x+4x+4+5=0 ⇒7x+9=0 x=−