R D Sharma Solutions for Chapter: Directions Cosines and Direction Ratios, Exercise 1: EXERCISE

Find the angle between the vectors whose direction cosines are proportional to $2, 3, -6$ and $3, -4, 5$.

Find the acute angle between the lines whose direction ratios are proportional to $2:3:6$ and $1:2:2$.

Find the angle between the lines whose direction ratios are proportional to $a, b, c$ and $b-c, c-a, a-b$.

If the coordinates of the points $A, B, C, D$ are $(1, 2, 3), (4, 5, 7), (-4, 3, -6)$ and $(2, 9, 2)$, then find the angle between $AB$ and $CD$.

Find the angle between the lines whose direction cosines are given by the equations
$l+m+n=0$ and $l^2+m^2-n^2=0$

Find the angle between the lines whose direction cosines are given by the equations
$2l-m+2n=0$ and $mn+nl+lm=0$

Find the angle between the lines whose direction cosines are given by the equations
$l+2m+3n=0$ and $3lm-4ln+mn=0$

Find the angle between the lines whose direction cosines are given by the equations
$2l+2m-n=0, mn+ln+lm=0$