`L_1a n dL_2` are two lines. If the reflection of `L_1onL_2` and the reflection of `L_2` on `L_1` coincide, then the angle between the lines is (a)`30^0` (b) `60^0` `45^0` (d) `90^0`

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

The direction cosines l, m and n of two lines are connected by the relations l+m+n=0 and lm=0 , then the angle between the lines is

The angle between a line x=1,y=2 and y+1=0, z=0 is (A) 0^0 (B) 30^0 (C) 60^0 (D) 90^0

The direction cosines of two lines satisfy 2l+2m-n=0 and lm+mn+nl=0 . The angle between these lines is

Let the straight lines x+y-2=0, 2x-y+1=0 and px+qy-r=0 be concurrent and l_1 and l_2 be the two members of the family of lines 2px+2qy+4r=0 which are nearest and farthest from origin : Now answer the question : The angle between lines L_1 and l_2 is : (A) 45^0 (B) 60^0 (C) 90^0 (D) none of these

In Figure, if l_1||l_2, what is the value of x ? (a) 90^0 (b) 85^0 (c) 75^0 (d) 70^0

The direction cosines of the lines bisecting the angle between the line whose direction cosines are l_1, m_1, n_1 and l_2, m_2, n_2 and the angle between these lines is theta , are

In Figure, if lines l\ a n d\ m are parallel lines, then x= (a) 70^0 (b) 100^0 (c) 40^0 (d) 30^0

Find the angle between the line whose direction cosines are given by l+m+n=0a n dl^2+m^2-n^2-0.

If l_1, m_1, n_2 ; l_2, m_2, n_2, be the direction cosines of two concurrent lines, then direction cosines of the line bisecting the angles between them are proportional to