<?xml version="1.0" encoding="UTF-8"?>
<quiz>
  <question type="description">
    <name>
      <text>5.2.27 (Summary of trig identities)</text>
    </name>
    <questiontext format="html">
      <text><![CDATA[<h3>Summary of trig identities</h3>

<p>We have covered a large number of trigonometric identities, which you are advised to remember. However, in many cases remember that we derived some of the formulas from the others. So it is probably easiest to remember the formulas you need to and then just derive the others from those that you remember. The most important identities and probably the ones most worth memorising are the following:</p>
<br/>
<p>
\(\begin{aligned}
\cos^2\theta+\sin^2\theta&amp;\equiv 1\\
\sin 2\theta&amp;\equiv 2\sin\theta\cos\theta\\
\cos 2\theta&amp;\equiv \cos^2\theta-\sin^2\theta\\
&amp;\equiv 2\cos^2\theta -1\\
&amp;\equiv 1-2\sin^2\theta\\
\sin (A\pm B)&amp;\equiv \sin A\cos B\pm\cos A\sin B\\
\cos (A\pm B)&amp;\equiv \cos A\cos B\mp\sin A\sin B\end{aligned}\)</p>]]></text>
    </questiontext>
    <generalfeedback format="html">
      <text/>
    </generalfeedback>
    <defaultgrade>0</defaultgrade>
    <penalty>0</penalty>
    <hidden>0</hidden>
    <idnumber/>
  </question>
</quiz>
