A YouTube video I'm watching just displayed the following equations without explanation ( https://youtu.be/WKU0qDpu3AM?si=90NXaNEGsdCilaBd&t=28 ). Can anyone identify them or what branch of math they're pulled from? (Beyond 'something to do with spherical coordinates'; I got that much.)
(there's a few sites that check for a cookie left by another site that says whether you're authorized or not, and if they don't find it, they leave one saying you're blocked and then default to that one even if you later get the authorized cookie)