Question

find the direction of cosines of a line which is perpendicular to the both of the lines with direction 4,1,3 and 2,-3,1​

Answer 1

$(1 \times 1) - 3( - 3)... - (4(1) - 1( - 3))....4( - 3) - 1(2)$

drs (1+9,-(4+3),-12-2)

=(19,-7,-14)