Question 730240
{{{tan^2(x) = sin^2(x)/cos^2(x)}}}<P>
{{{sin^2(x) + cos^2(x)=1}}} so {{{cos^2(x) = 1-sin^2(x)}}}<P>
So the expression becomes {{{(1-2*sin^2(x))/(1-sin^2(x)) + sin^2(x)/(1-sin^2(x))}}}<P>
They have the same denominator, so now add them.<P>
Look at the denominators:  {{{1-2*sin^2(x) + sin^2(x) = 1-sin^2(x)}}}<P>
That goes over the common denominator:  {{{(1-sin^2(x))/(1-sin^2(x)) = 1}}}