I've been teaching all day, and all I've been able to discover so far is that the whiteboard in my office is too small to slog though all these sinθcosϕ-looking terms

@ColinTheMathmo @henryseg @dlzv Thanks for taking an interest y'all! Here's some more context for ya:

The actual question is to find the straight-line distance between two points on the earth given their GPS coordinates. So yeah $r$ is fixed. My goal is to find out if this is a suitable question to give a precal class who I just showed the law of cosines, and I think this hinges on whether or not we can find that angle without vector/dot-product action.

I'm a math instructor living in CO. Came here to claim my nice @mikepierce username in case there's a mass migration from twitter.

Right now trying to figure out the nicest way to calculate the angle between two rays in 3-dimensional space given their "spherical coordinate" angles

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