sin(-a)sin【5/(2-a)】tan(a-2π)/cos【a-（π/2）】cos【a-（3π/2）】-tan（π-a）tan【（3π/2）-a】=-sin(a)sin【5/(2-a)】tan(a)/cos【（π/2）-a】cos【（3π/2）-a】-tan(a)tan(π/2-a)
=-sin(a)sin【5/(2-a)】tan(a)/sin(a)cos(a)-tan(a)cot(a)
=-sin【5/(2-a)】tan(a)/cos(a)-tan(a)cot(a)