GivenDirection ratios as -18,12,-4Where, a=-18, b=12, c=-4Let us consider the direction ratios of the line as a, b and cThen the direction cosines area2+b2+c2​a​,a2+b2+c2​b​,a2+b2+c2​c​ Where,a2+b2+c2​​=(−18)2+122+(−4)2​=324+144+16​=484​=22​ ∴ The direction cosines are-18 / 22,12 / 22,-4 / 22=>-9 / 11,6 / 11,-2 / 11