Question 900728
<pre>
{{{system(cos^2(alpha)+sin^2(alpha)=tan^2(beta),matrix(1,2,prove, "that:"),cos^2(beta)+sin^2(beta)=tan^2(alpha) )}}}

That's not true because if {{{alpha="30°"}}} and {{{beta="45°"}}}

{{{system(cos^2("30°")+sin^2("30°")=tan^2("45°"),matrix(1,1,"however,"),cos^2("45°")+sin^2("45°")<>tan^2("30°") )}}}

Because, evaluating:

{{{system(3/4+1/4=1,however,1/2+1/2<>1/3)}}}

Edwin</pre>