Assuming : 1/(1-cosx) +1/(1+cos x)
= (1+cosx + 1-cosx)/((1-cosx)(1+cosx))
= 2/(1 - cos^2 x) <------ did you notice the difference of squares
using sin^2 x + cos^2 x = 1, I will let you take another step
Simplify :1/1-cosx +1/1+cos x
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