#(csc theta)(sec theta - cos theta)#
# =(1/(sin theta))(1/(cos theta) - cos theta)#
#=1/(sin theta)(1/(cos theta) - ((cos theta)/1)((cos theta)/(cos theta)))#
#=1/(sin theta)(1/(cos theta) - (cos theta)^2/(cos theta))#
#=1/(sin theta)((1-(cos theta)^2) /(cos theta))#
#=1/(sin theta)((sin theta)^2/(cos theta))#
#=(sin theta)/(cos theta)#
# =tan theta #