## Problem on the right hand rule

Use the right hand rule to determine:
1. Does $\bfi \times \bfj$ equal $\bfk$ or $-\bfk$?
2. Does $\bfk \times \bfi$ equal $\bfj$ or $-\bfj$?
3. Does $\bfk \times \bfj$ equal $\bfi$ or $-\bfi$?
• ## Solution

Recall the right hand rule:
(a) If we align the fingers of our right hands with $\bfi$ in such a way that we can curl them toward $\bfj$, then our right palm must be facing toward $\bfj$ and our right thumb points toward positive $\bfk$.
Hence, $\bfi \times \bfj = \bfk$.
(b) If we align the fingers of our right hand with $\bfk$ in such a way that we can curl them toward $\bfi$, then our right palm must be facing toward $\bfi$ and our right thumb points toward positive $\bfj$.
Hence, $\bfk \times \bfi = \bfj$.
(c) If we align the fingers of our right hand with $\bfk$ in such a way that we can curl them toward $\bfj$, then our right palm must be facing toward $\bfj$ and our right thumb points toward negative $\bfi$.
Hence, $\bfk \times \bfj = -\bfi.$