If `l_(1),m_(1),n_(1)` and `l_(2),m_(2),n_(2)` are the directional cosines of two vectors and `theta` is the angle between them, then their value of `cos theta` is

If l_(1), m_(1), n_(1) and l_(2), m_(2), n_(2) are the direction cosines of two vectors and theta is the angle between them, then the value of cos theta is

If lt l_(1), m_(1), n_(1)gt and lt l_(2), m_(2), n_(2) gt be the direction cosines of two lines L_(1) and L_(2) respectively. If the angle between them is theta , the costheta=?

If (l_(1),m_(1),n_(1)) and (l_(2),m_(2),n_(2)) are the direction cosines of two lines find the direction cosines of the line which is perpendicular to both these lines.

If l_(1), m_(1), n_(1) and l_(2), m_(2), n_(2) are the direction cosines of two lines and l , m, n are the direction cosines of a line perpendicular to the given two lines, then

If l_(1), m_(1), n_(1) and l_(2), m_(2), n_(2) are direction cosines of two mutually perpendicular straight lines, then prove that the direction cosines of the straight line which is perpendicular to both the given lines are pm (m_(1)n_(2)-m_(2)n_(1)), pm (n_(1)l_(2)-n_(2)l_(1)), pm (l_(1)m_(2)-l_(2)m_(1))

If l_1,m_1,n_1 and l_2,m_2,n_2 are the direction cosines of two rays OA and OB making an angle theta then show that the direction cosines of the bisector of /_AOB are (l_1+l_2)/(2cos(theta/2)),(m_1+m_2)/(2cos(theta/2)),(n_1+n_2)/(2cos(theta/2))