How to prove (1-sin theta) / cos theta = cos theta / (1 + sin theta) ?

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Answer 1 · 2018-04-21T17:47:21

Please see the proof below

We need

#cos^2theta+sin^2theta=1#

Therefore,

#LHS=(1-sintheta)/costheta#

#=((1-sintheta)(1+sintheta))/((costheta)(1+sintheta))#

#=(1-sin^2theta)/(costheta(1+sintheta))#

#=(cos^2theta)/(costheta(1+sintheta))#

#=costheta/(1+sintheta)#

#=RHS#

#QED#