[" 36) Show that the straight lines whose direction cosines are given by "21+2m-n=0" and "],[mn+n1+Im=0" are at right angles."]

Show that the straight lines whose direction cosines are given by 2l + 2m - n = 0 and mn + nl + Im = 0 are at right angles.

Find the angle between the two straight lines whose direction cosines are given by 2l+2m-n=0, mn+nl+lm=0

Find the angle between the lines whose direction cosines are given by : 2l-m+2n=0, mn+nl+lm=0 .

Prove that the straight lines whose direction cosines are given by a^(2)l+b^(2)m+c^(2)n=0 and mn+nl+lm=0 are parallel if a+b+c=0 .

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

The angle between the lines whose directionn cosines are given by 2l-m+2n=0, lm+mn+nl=0 is

The angle between the lines whose directionn cosines are given by 2l-m+2n=0, lm+mn+nl=0 is

Show that the pair of lines whose direction cosines are given by 3lm-4ln+mn=0 and l+2m+3n=0 are perpendicular to each other.

The angle between the straight lines, whose direction cosines are given by the equations 2l+2m -n=0 and mn+nl+lm=0 , is :