If lines are Ax + By + $C_1$ = 0 and Ax + By + $C_2$ = 0, then distance between parallel lines, d = $\frac{\left|C_1-C_2\right|}{\sqrt{A^2+B^2}}$ (i) Here, A = 15, B = 8, $C_1$ = – 34, $C_2$ = 31 d = $\frac{\left|-34-31\right|}{\sqrt{(15)^2+(8)^2}}$ = $\frac{65}{17}$ units (ii) The line can be re-written as lx + ly + p = 0 and lx + ly – r = 0 Here A = l, B = l, $C_1$ = p, $C_2$ = –r d = $\frac{\left|p+r\right|}{\sqrt{(l)^2+(l)^2}}$ = $\frac{p+r}{l\sqrt{2}}$ units