A ray of light is incident along a line which meets another line 7x...

Let slope of incident ray be $m .$

$∴$ angle of incidence = angle of reflection

$∴$ \left|\dfrac{m - 7}{1 + 7m}\right| = \left|\dfrac{- 2 - 7}{1 - 14}\right| = \dfrac{9}{13}$<br /><br />$⇒ \dfrac{m - 7}{1 + 7m} = \dfrac{9}{13}or\dfrac{m - 7}{1 + 7m} = - \dfrac{9}{13}$<br /><br />$⇒ 13m - 91 = 9 + 63m$, or$13m - 91 = - 9 - 63m$<br /><br />$⇒ m = -2$or$m = \dfrac{41}{38}$<br /><br />$⇒ y - 1 = \dfrac{41}{38}\left(x - 0\right)$<br /><br />$⇒ 38y - 38 - 41x = 0