докажите тождество ctgt*sin^2t=(tgt+ctgt) ^-1

1) ctgt*sin^2t=(cost/sint)*sin^2t=cost*sint2) (tgt+ctgt) ^-1=(sint/cost)+cost/sint) ^-1=(sin^2t+cos^2t) / (cost*sint) ^-1=(1/ (cost*sint) ^-1=cost*sint1)=2) cost*sint=cost*sint