Question 291497
Prove tan squared theta times cos squared theta minus 1 divided by tan squared = 1


{{{(Tan^2theta*Cos^2theta-1)/(Tan^2theta)=1}}}

That can't be prove for it isn't true.  For if {{{theta="45°"}}}, then

{{{Tan(theta)=1}}} and {{{Cos(theta)=sqrt(2)/2}}}

{{{((1)^2*(sqrt(2)/2)^2-1)/(1)^2=1}}}

{{{((1)*(2/4)-1)/1=1}}}

{{{1/2-1=1}}}

{{{-1/2=1}}}

And that just isn't true, so it isn't true for all {{{theta}}}.

Edwin</pre>