# Math Help - Orthogonal vectors

1. ## Orthogonal vectors

I'm not sure how to do part a) and b). For a) I don't get how the hint helps.

Eg, I did $P_1P_2 = \frac{1}{||a||^2}aa^T\frac{1}{||b||^2}bb^T$ and we know that a.b = 0 but there are no dot products in the former equation...

Cheers!

2. Originally Posted by usagi_killer

I'm not sure how to do part a) and b). For a) I don't get how the hint helps.

Eg, I did $P_1P_2 = \frac{1}{||a||^2}aa^T\frac{1}{||b||^2}bb^T$ and we know that a.b = 0 but there are no dot products in the former equation...
In fact, there is a (disguised) dot product in that equation, because $a^{\textsc t}b$ is just another way of writing $a.b$.