<p>yay i just got a ti-89 and skimmed the manual. </p>
<p>how would you solve the problem on the calculator: </p>
<p>If cos x = (1/6), what is (sin2x/sinx)?</p>
<p>w/out getting the @2n or w/e . </p>
<p>and what are the most useful programs?? i know there was a thread on programs already but i cant find it.</p>
<p>ooo great question. I would also like to know. (Actually, I did it my hand when I was studying that stuff because my cal couldn't take it and none of my friends and teacher know what it is)</p>
<p>well you don't really need a calculator for it... sin2x/sinx is the same thing as (2sinxcosx)/sinx => 2cosx. if cosx is 1/6, 2cosx is 2/6 or 1/3</p>
<p>all you have to do is set a domain in your calculator. so you can use the solve function and do f(x)=answer,x and type in the bar on the left side of the calculator, and then put x>0 and (you find and in the catalog) x<2pi</p>
<p>so it'll look like solve(f(x)=y,x)|x>0 and x<2pi</p>
<p>you could also do on a ti-83 Sin(2cosine inverse (1/6))/Sin(Cosine inverse (1/6))</p>