Question 1078820
<pre><b>
{{{6 sec^2(x) + 3 tan^2(x) - 9 = 0}}}

{{{6(1+tan^2(x)^"")+3tan^2(x)-9=0}}}

{{{6+6tan^2(x)+3tan^2(x)-9=0}}}

{{{9tan^2(x)-3=0}}}

{{{9tan^2(x)=3}}}

{{{tan^2(x)=1/3}}}

{{{tan(x)="" +- sqrt(1/3)}}}

{{{tan(x)="" +- sqrt(3)/3}}}

You finish by yourself, using your knowledge of the special angles.

Edwin</pre></b>