So as the title states I have to evaluate
sin−1(cos(40))
In my textbook they answer it as following:
sin−1(cos(40))=90−cos−1(cos(40))=50
I'm however a little confounded over their answer.
As I recall this is the complementary angle identity but I don't really understand why it is used, considering is within the bound of [-1,1]
Would be extremely grateful if somebody could expand. If my question is unclear, I would be more than happy to further clearify.
Thank you in advance!
