To simplify #cos(x+2pi)/sinx#, first one may note that adding #2pi# or its multiple, to a trigonometric ratio, does not change its value
i.e. #sin(x+2npi)=sinx# (for all #n#, where #n# is an integer), #cos(x+2npi)=cosx#, #tan(x+2npi)=tanx#, #cot(x+2npi)=cotx#, #sec(x+2npi)=secx# and #csc(x+2npi)=cscx#.