How do you evaluate #cos^-1(sin(7pi/2))#?
For any a,
Use bijective 1-1 inversion
Despite that both
rotation is opposite, for the negative sign. So, I make this self-
correction to my previous answer from
See how it works, in the reverse process.
Interestingly, owing to the principal value convention, your
calculator gives the answer as
calculation, it gives