What is the magnitude of the cross product?

What is the magnitude of the cross product vec{A} times vec{B}?

What is the magnitude of the cross product vec{C} times vec{D}?

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