Question

how did this come about?
file attached below
cos12 is around 4pi-12?

Answer 1

12 is in radians

Answer 2

It's important to realise that the cosine and sine functions repeat every 2pi radians.
It looks like this:

Answer 3

why is it 4pi-12 for cosine and 12-4pi for sine?

Answer 4

Because it works both ways. If you add multiples of 2pi you get to the same result, but if you subtract multiples of 2pi you also get the same result.
I.e: cos(x)=cos(x+2pi)=cos(x+4pi)=cos(x-2pi)=cos(x-4pi)

Answer 5

thank you people got it!