Question 1155028
<pre>
{{{2sin^2(x)-cos(x) =1}}}

{{{2sin^2(x)-cos(x)-1=0}}}

{{{2(1^""-cos^2(x))-cos(x)-1=0}}}

{{{2-2cos^2(x)-cos(x)-1=0}}}

{{{-2cos^2(x)-cos(x)+1=0}}}

Multiply through by -1

{{{2cos^2(x)+cos(x)-1=0}}}

Factor the left side:

{{{matrix(1,3,(cos(x)+1)(2cos(x)-1),""="",0)}}}

Use the zero factor principle:

{{{matrix(4,3,

cos(x)+1=0,"",2cos(x)-1=0,
cos(x)=-1,"",2cos(x)=1,
x=pi,"",cos(x)=1/2,
""  ,"", x=matrix(1,3,pi/3,and,5pi/3) )}}}

Edwin</pre>