What is the magnitude of the cross product?

3 Answers

• If a vector b makes an angle θ with vector a.

  The magnitude of the cross product is :

         |a X b| = |a|.|b|sinθ

  In your examples

  (a) |a| = 6 and |b| = 4 θ = 180° – 135° = 45°

         |a X b| = 6 X 4 X sin(45°)
  
                   = 24(1/√2)
  
                   = 12√2 units  (Multiplying top and bottom be √2)

  (b) In this case vectors are anti parallel so θ = 180°

            |c X d| = 0  since sin(180°) = 0.

• Magnitude Of Cross Product

• http://en.wikipedia.org/wiki/Cross_product#Definit…

  simple problem. why not try and post back if you get stuck. you’ll be better off down the road if you at least try…

  cheers