Aiming at the defect in designing crank-rocker mechanism by transmission angels

the existence and uniqueness of closed-form solution for designing crank-rocker mechanism by γmin≥[γ] is proved."γmin≥[γ]" is turned into an one-variable inequality

and it is proved the fact that "γmin≥[γ]"is of the same solution with the one-variable quadratic inequality with parameters.The possible formula of parameters from the relations of the one-variable inequality is dericed

and the impossible formula of parameters is exeluded based on uniqueness of closed solution.Finally

the closed-form solution is determined.