Question 1120627
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The expression is a perfect square trinomial....<br>
{{{2(cos(x))^2-(2*sqrt(2))(cos(x))+1 = 0}}}
{{{(sqrt(2)*cos(x)-1)^2 = 0}}}
{{{sqrt(2)*cos(x)-1 = 0}}}
{{{sqrt(2)*cos(x) = 1}}}
{{{cos(x) = 1/sqrt(2)}}}<br>
x = 45 degrees or 315 degrees, plus or minus any multiple of 360 degrees.