Question 293733
<pre><font size = 4 color = "indigo"><b>
{{{Cos(2x)= (1-Tan^2x)/(1+Tan^2x)}}}
{{{Cos(2x)= (1-Tan^2x)/(Sec^2x)}}}
{{{Cos(2x)= (1-Tan^2x)*(1/(Sec^2x))}}}
{{{Cos(2x)= (1-Tan^2x)*(Cos^2x)}}}
{{{Cos(2x)= Cos^2x-(Tan^2x)*(Cos^2x)}}}
{{{Cos(2x)= Cos^2x-((Sin^2x)/(Cos^2x))*(Cos^2x)}}}
{{{Cos(2x)= Cos^2x-((Sin^2x)/(cross(Cos^2x)))*(cross(Cos^2x))}}}
{{{Cos(2x)= Cos^2x-Sin^2x}}}
{{{Cos(2x)= Cos(2x)}}}

Edwin</pre></font></b>