Respuesta :

Explanation:
cot(x−π/2)= -tanx
Left Side :=cot (x−π/2)=
cos(x−π/2)/sin(x−π/2)
=cosxcos(π/2)+sinxsin(π/2)/sinxcos(π/2)−cosxsin(π/2)
=cosx(undef)+sinx⋅1/sinx(undef)−cosx⋅1
=sinx/−cosx
=−tanx