z is a complex number; z = x+iy
z-bar is a complex conjugate; z-bar = x-iy
need to show: sin(z-bar) is not differentiable everywhere
formulas (if needed):
2) Cauchy Riemann equations
problem is i dunno how to express sin(z) as real u(x,y) + iv(x,y). I'm not even sure if C-R is the best way to go about solving this problem.