Difference between phi, psi and theta when dealing with trig?
While going over some math concepts (on 3D rotation matrices) I stumbled on trig functions with phi and psi. Up until this point, I typically saw trig functions with the theta notation.
So my question is, what is meant by sin phi or sin psi. What is the difference between phi, psi, and theta?
So my question is, what is meant by sin phi or sin psi. What is the difference between phi, psi, and theta?
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I've never seen psi used before, though looking it up it seems common in the chemistry fields. Phi I see a lot when dealing with spherical coordinate systems. I think typically it's just used as a second symbol for an angle after theta.
None. The only reason you'll find it is cases with two different angles being measured- in the same way that, when working with 3 axis, you end up going from x to y to z or a to b to c. It's just the way of saying "angle one" and "angle two" in the same formula.
To OP: angle letters are chosen entirely by convention. Nothing is standard about those. In Bulgaria we rarely use \theta to denote angles, we use \phi in the place where american schools use theta (in spherical coordinates, say), and \psi in the place where american schools use \phi (in spherical coordinates). That said, I am currently an instructor of calculus in an american institution, so I am more used to the US convention now.
In Bulgaria we use \phi to measure diameter of cross-section (of a pipe). Bulgarian engineers would use \phi as synonym of "diameter". That use of \phi is completely unrelated to use of \phi in spherical coordinates/rotation matrices. However, the use of \phi as synonym of "diameter" is very relevant to this:
Three women are bragging about the size of their men's manhoods.
The first woman: my man's is 15cm!
Second woman: hahaha my man's 20cm!
Third woman: my man's 5cm.
First and second woman: Hi hi hi hi ...
Third woman: No, no, it's phi !
In Bulgaria we use \phi to measure diameter of cross-section (of a pipe). Bulgarian engineers would use \phi as synonym of "diameter". That use of \phi is completely unrelated to use of \phi in spherical coordinates/rotation matrices. However, the use of \phi as synonym of "diameter" is very relevant to this:
Three women are bragging about the size of their men's manhoods.
The first woman: my man's is 15cm!
Second woman: hahaha my man's 20cm!
Third woman: my man's 5cm.
First and second woman: Hi hi hi hi ...
Third woman: No, no, it's phi !
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