<PRE><B>Question 1171886</B>
cos x=-sqrt(3)/2
this occurs at (5/6)π=2πn and (7/6)π+/-2πn
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(2 sin x+1)(sin x -1)=0
sin x=1 and sin x=-1/2
π/2, 7π/6, 11π/6, with the +/-2πn
{{{graph(300,300,-6,6,-1,1,2*(sin(x))^2-sin(x)-1)}}}
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2 sin^2 x=2+(1-sin^2 x)
3 sin^2x=3
sin^2x=1
x=π/2, and 3π/2 with +/-2πn</PRE>