radical Defined by vector Cross multiplication, (→A)X(→B)=(→C)

vector c= vector a× vector b=

|i j k |

|a1 a2 a3|

|b1 b2 b3|

=(a2b3-a3b2,a3b1-a1b3,a1b2-a2b1)

(i, j and k are the unit vectors of three coordinate axes perpendicular to each other in spatial)