TanB = b/a
In general terms, TanB = opposite/adjacent. We write "Tan" as the shorthand form for tangent.
Naturally, SOH CAH TOA helps us remember tangent as well. As you can probably guess by now, the "TOA" component stands for "Tangent is Opposite over Adjacent."
Again, try it out for yourself to see how all these functions work. See that in this triangle:
TanB = 3/4, so...
B = 36.87 degrees
These are the basic definitions for the standard trig functions, and they all work the same way to provide you with the same measurements for the angles or sides... the only things that are different are the sides that are being included in the ratios! So, pay attention to what sides you are looking at!