<p>Do we need to know them? I think double angle formulas would come in handy, but what about half angles and sum/diff formulas?</p>
<p>bump 10 char. Please answer! It’s a very simple question…</p>
<p>I don’t recall any half angle or sum/difference questions on the June 2010 test. If you’re paranoid, you could always store them in your calculator (or use a calculator with a CAS (e.g. the TI-89) and have the calculator spit out the formula).</p>
<p>haha I already programmed double angle stuff into my calc…
thank you!</p>
<p>why would you need that.</p>
<p>Sin (47) => use calculator
Sin (A+B) => sinAcosB+sinBcosA</p>
<p>because…you either memorize it (which i already did ages ago) or you just plug it into your calculator if you don’t know it or you do both to be safe.</p>