2cos^2x/2(1-sinx)-cos^2=0

Question

2cos^2x/2(1-sinx)-cos^2=0

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Answer 1

(1+cosx)(1-sinx)-(1-sinx)(1+sinx)=0
(1-sinx)(1+cosx-1-sinx)=0
cosx=sinx
tgx=1
x=п/4+пk, k Z
1-sinx=0
sinx=1
x=П/2+2Пk