Because cos(2x)=cos(-2x)=cos(2x+2kpi)=cos(-2x+2kpi) ^^
Originally Posted by Kaitosan
cos(-2x)=cos(2x+2kpi)
What? You didn't even explain how you came about that answer. What is the reasoning behind this? I don't get it. Please repeat.
arccos and cos are inverse operators so they cancel each other out giving the solution of 2x. The 2kpi is because cos(2x) repeats itself every pi radians
Thanks guys. I didn't know that if cosx is within its inverse, they cancel each other. Is this also the case with arcsin(sinx) = x and arctan(tanx) = x? What about tan(arctanx) and cos(arccosx) or something?
Thanks guys. I didn't know that if cosx is within its inverse, they cancel each other. Is this also the case with arcsin(sinx) = x and arctan(tanx) = x? What about tan(arctanx) and cos(arccosx) or something?