Find the value of cos theta/1-sin theta + cos theta/1+sin theta=4?

See below
##cos theta/(1-sin theta) + cos theta/ (1+sin theta) = 4##
##(cos theta (1+sin theta)+cos theta(1-sin theta))/((1-sin theta)(1+sin theta)) =4##
##(cos theta + sin theta cos theta+ cos theta-sin theta cos theta)/(1-sin^2 theta)=4##
##(2cos theta)/cos^2 theta = 4##
##2/cos theta =4##
##2=4cos theta##
##1/2 = cos theta##
##theta = cos^-1 (1/2)##
##theta=+- 60 + 360^@n##