® Angle between skew lines is the angle between two intersecting lines

® Angle between skew lines is the angle between two intersecting lines drawn from any point (preferably through the origin) parallel to each of the skew lines. ® If l 1 , m 1 , n 1 and l 2 , m 2 , n 2 are the direction cosines of two lines; and θ is the acute angle between the two lines; then cos θ = | l 1 l 2 + m 1 m 2 + n 1 n 2 | 392 ® If a 1 , b 1 , c 1 and a 2 , b 2 , c 2 are the direction ratios of two lines and θ is the acute angle between the two lines; then cos θ = a a c c