Direction ratios of the given lines are respectively< 2, 5, –3> and < –1, 8, 4> Let θ be the angle between the given lines, then where $a_1, b_1, c_1$ and $a_2, b_2, c_2$ are direction ratios$\cos \theta$ $= \frac{\left| 2 \times (-1) + 5 \times 8 + (-3) \times 4 \right|}{\sqrt{2^2 + 5^2 + (-3)^2} \sqrt{(-1)^2 + 8^2 + 4^2}}$$= \frac{26}{\sqrt{38} \sqrt{81}} = \frac{26}{9 \sqrt{38}}$$\Rightarrow \theta = \cos^{-1} \frac{26}{9 \sqrt{38}}$