1. The problem statement, all variables and given/known data Show that sin(z) satisfies the condition. (Stated in the title) 2. Relevant equations 3. The attempt at a solution f(z) = sin (z) = sin (x + iy) = sin x cosh y + i cos x sinh y thus, u(x,y)=sin x cosh y ....... v(x,y)= cos x sinh y du/dx = cos x ............ dv/dx = -sin x du/dy = -sinh y ........... dv/dy = cosh y therefore I will compare it with the Cauchy Riemann formula. Am I right to say it doesn't satisfies the condition??