Show that the lines whose d.c's are given by l + m + n = 0,2mn + 3nl - 5ln = 0 are perpendicular to each other.

Show that the lines whose direction cosines are given by l+m+n=0 , 2mn+3nl-5lm=0 are perpendicular to each other .

Find the angle between the lines whose d.c's are related by l + m + n = 0 & l^(2) + m^(2) - n^(2) = 0

Find the angle between the lines whose direction cosines are given by the equation 3l + m + 5n = 0 and 6mn - 2nl + 5lm = 0

If the direction rations of two lines are given by 3lm-4ln+mn = 0 and l + 2m + 3n = 0 then the angle between the lines is