Question 1195997
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(1) Note your post contains no question....<br>
No matter how obvious it is what your question is, the polite thing to do in your post is ask the question.<br>
(2) There is no standard use of the "\" symbol, so I don't know what to make of "(2\alpha +(\pi )/(4))"....<br>
But the equation is of the form {{{cos(x)=3tan(x)}}}, which can be solved for x:<br>
{{{cos(x)=3tan(x)}}}
{{{cos(x)=(3sin(x))/cos(x)}}}
{{{(cos(x))^2=3sin(x)}}}
{{{1-(sin(x))^2=3sin(x)}}}
{{{(sin(x))^2+3sin(x)-1=0}}}<br>
That does not factor over the integers, so use the quadratic formula.
{{{sin(x)=(-3+sqrt(13))/2}}}<br>
The other root produces an invalid value for sin(x), so it can be ignored.<br>
But, since I have no idea what your post means, I don't know if that is of any help to you....<br>