sinx = 2tan(x/2)/(1+tanx/2tanx/2) = 2*sqrt(5)/(1+5) = sqrt(5)/3cosx = (1-tanx/2tanx/2)/(1+tanx/2tanx/2) = -2/3（1+sinx-cosx)/(1+sinx+cosx）= (1+ sqrt(5)/3+2/3)/(1+ sqrt(5)/3-2/3)= sqrt(5)...