do it step by step will it work yes
The way you worded the question kind of confuses me but i'll try to answer.
Think of recursion like climbing a ladder; in this type of sequence you start out somewhere, usually n. So in f(n-1)+1, you take n (where you started) and "step down" once, and then step up once (which brings you back where you were). Remember PEMDAS when doing these.
cos0 = √3/2
1 - cos²0 = sin²0
= 1/4 = sin²0
sin in quadrant 4 is negative
sin0 = -1/2
I believe it is B and C. (Side note, I got the same computer from K-12 lol I’m in 8th grade and this is my first year, will it get easier?!?)
