Question 253719
<pre>
{{{Tan(x) (Cot(x) + Tan(x)) = Sec^2x}}} 

{{{Tan(x)*Cot(x) + Tan^2x = ""}}}

{{{Tan(x)(1/(Tan(x))) + Tan^2x = ""}}}

{{{cross(Tan(x))(1/(cross(Tan(x)))) + Tan^2x = ""}}}

{{{1 + Tan^2x = ""}}}

{{{Sec^2x = ""}}}

Edwin</pre>