I need to prove sin(cosx)=0, but I'm looking through all of my identities and none of them seem to fit? Any help on this would be great!
Thank you!
Brittney
this equation is not true for all x (not an identity) ... it is a conditional equation, so there is nothing to "prove".
since $\displaystyle \sin(something) = 0$ , then $\displaystyle something$ has to be 0 or an integer multiple of $\displaystyle \pi$.
since $\displaystyle -1 \le \cos{x} \le 1$ , none of the multiples of $\displaystyle \pi$ will work, therefore $\displaystyle \cos{x}$ can only equal 0.
I leave you to determine those values of x that make $\displaystyle \cos{x} = 0$