#cotx+sinx=-cosxcotx#
#cos x/sin x+sinx=-cosx cosx/sinx#
#(cos x+sin^2x)/sinx=-cos^2x/sinx#
#(cos x+sin^2x)/sinx *sinx=-cos^2x/sinx *sinx#
#(cos x+sin^2x)/cancelsinx *cancelsinx=-cos^2x/cancelsinx *cancelsinx#
#cos x+sin^2x=-cos^2x#
#cos x+sin^2x+cos^2x=0#
#cosx+1=0#
#cosx=-1#
#x=cos^-1 (-1)#
#:.x=+-pi+2pin#