Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Trying to see how these are equivalent

  1. Apr 15, 2014 #1
    I am working on the derivation of the angular momentum squared operator (in quantum mech.) and there is one step that I dont see how it works. I'm not sure that this is the right place to post it, but since this is a strictly mathematical question, I figured I would post it here. The equivalence is as follows:

    (cotθ)(∂/∂θ) + (∂/∂θ)2 = (cscθ)(∂/∂θ)[(sinθ)(∂/∂θ)]

    I dont see how to go from one to the other
  2. jcsd
  3. Apr 15, 2014 #2


    Staff: Mentor

    Start on the right side, and take the derivative of (sinθ * (∂/∂θ)), using the product rule. This simplifies to what you have on the left side without too much effort.
  4. Apr 15, 2014 #3
    Thanks :-) I dont know why I didnt try that
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook