At 3:55 we have $\tan 34.4^\circ=9.16/b$, and the kind sir says that to calculate $b$ he needs to change the equation to $b = 9.16/\tan 34.4^\circ$.
I've seen this trick used alot before, but I never seem to grasp it. What is the logic behind him changing the order? How do I know what to divide or multiply?
Does the trick have a name? I've tried to search for "rearranging formula" like it said in the video, but it didnt get me far.
I hope I used the right tag.