The distance between two skew lines with equations x | = | x_1 + (x_2 - x_1) s x | = | x_3 + (x_4 - x_3) t is given by D = ( left bracketing bar (x_3 - x_1)·[(x_2 - x_1)x(x_4 - x_3)] right bracketing bar )/( left bracketing bar (x_2 - x_1)x(x_4 - x_3) right bracketing bar ) . This can be written in the concise form D = ( left bracketing bar c·(axb) right bracketing bar )/( left bracketing bar axb right bracketing bar ) by defining a | congruent | x_2 - x_1 b | congruent | x_4 - x_3 c | congruent | x_3 - x_1.

line-line angle | line-line intersection | skew lines