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I couldn't figure out the direction of this specific cross product example because of the angle. I tried the right hand rule several times but I can't seem to get it right. How did the direction turn out to be like this? And how should I shape my hand?

enter image description here

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    $\begingroup$ If you’re having a problem visualizing the right-hand-rule for $\vec{F_1}\times\vec{F_2}$ because you have to put your right hand into an awkward position, try it for $\vec{F_2}\times\vec{F_1}$, which is in the opposite direction. Or use your left hand and reverse the result. $\endgroup$ – G. Smith Dec 5 '19 at 16:59
  • $\begingroup$ As far as it seems to me that $F_2$ is coming out of the paper (in z-direction) and not in $xy$ plane. $\endgroup$ – user240696 Dec 5 '19 at 17:38
  • $\begingroup$ @Knight Out of the paper but not in the $z$-direction. Look at the indicated angle of 120 degrees with the $x$-axis. $\endgroup$ – G. Smith Dec 5 '19 at 17:43
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    $\begingroup$ I've added the homework-and-exercises tag. In the future, please add this tag to this type of problem. This is one of the things that we ask you to do in our homework policy: physics.meta.stackexchange.com/questions/714/… $\endgroup$ – user4552 Dec 5 '19 at 21:58
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    $\begingroup$ Please reference the source of this homework question. This is one of the things that we ask you to do in our homework policy: physics.meta.stackexchange.com/questions/714/… $\endgroup$ – user4552 Dec 5 '19 at 21:58
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I like the following configuration

RHRule

To get $\vec{a} \times \vec{b}$ make your fingers sweep from one vector to the other, as if you are rotating $\vec{a}$ to meet $\vec{b}$ (dashed arrow below).

The cross product direction is where your thumb points.

In your question specifically, put the base of the fingers at $\vec{F}_1$ and the tips of the fingers at $\vec{F}_2$.

Answer

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  • $\begingroup$ Why the downvote without comment? $\endgroup$ – John Alexiou Dec 6 '19 at 22:23

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