It's really simple actually... Because it is a CIRCLE, 2-dimensional shape, the scalar triple products are all equal to zero...

Three vectors in a 2D plane are always linearly dependent.

I'm going to check out your links, thanks ganesh.]]>

To do it algebraically, just do:

a = <a1, a2, a3>

b = <b1, b2, b3>

c = <c1, c2, c3>

And then compute each dot/cross product.

]]>I have no idea how to apply the diagram.]]>