What is the unit vector that is orthogonal to the plane containing (29i-35j-17k) and (41j+31k) ?

1 Answer
Apr 2, 2017

The unit vector is =1/1540.3〈-388,-899,1189〉

Explanation:

The vector perpendicular to 2 vectors is calculated with the determinant (cross product)

| (veci,vecj,veck), (d,e,f), (g,h,i) |

where 〈d,e,f〉 and 〈g,h,i〉 are the 2 vectors

Here, we have veca=〈29,-35,-17〉 and vecb=〈0,41,31〉

Therefore,

| (veci,vecj,veck), (29,-35,-17), (0,41,31) |

=veci| (-35,-17), (41,31) | -vecj| (29,-17), (0,31) | +veck| (29,-35), (0,41) |

=veci(-35*31+17*41)-vecj(29*31+17*0)+veck(29*41+35*0)

=〈-388,-899,1189〉=vecc

Verification by doing 2 dot products

〈-388,-899,1189〉.〈29,-35,-17〉=-388*29+899*35-17*1189=0

〈-388,-899,1189〉.〈0,41,31〉=-388*0-899*41+1189*31=0

So,

vecc is perpendicular to veca and vecb

The unit vector in the direction of vecc is

=vecc/||vecc||

||vecc||=sqrt(388^2+899^2+1189^2)=sqrt2372466

The unit vector is =1/1540.3〈-388,-899,1189〉