The direction cosines of a line / are the cosines of the direction angles, where the direction angles α, β, and γ are the angles between a vector along the line / and the positive directions of, respectively, the Ox-axis, Oy-axis, and Oz-axis of a rectangular coordinate system. The direction cosines are related by the equation
cos2α + cos2β + cos2 γ = 1
Figure 1. Directional blasting: (a) ejection blasting using blasthole charge, (b) ejection blasting using two chamber charges, (c) collapse blasting using blasthole charge, and (d) collapse blasting using chamber charge; (1) free surface of mass, (2) explosive charge, (3) trajectory of rock fragments, (4) contour of blasting excavation, (5) heap of rock after blasting, (6) explosive charge detonated in second phase, (7) trajectory of fragments from second explosion, (8) heap of rock after second explosion, and (9) contour of excavation after second explosion