Question

Ж: П/2+Пn,П+2Пn,nэz

Answer 1

Sin^2(x)+cos^2(x)=1
sin^2(x)=1-cos^2(x)
1-cos^2(x)=cosx+1
1-cos^2(x)-cosx-1=0
-cos^2(x)-cosx=0
-cosx(cosx+1)=0
cosx=0, x=p/2+pk.
cosx+1=0
cosx=-1, x=p+2pk.