<p>An illustration of which trigonometric functions are positive in which quadrants:
</p>
<ul><li>In Quadrant I, <b>a</b>ll of the functions are positive.</li>
<li>In Quadrant II, <b>s</b>ine is positive.</li>
<li>In Quadrant III, <b>c</b>osine is positive.</li>
<li>In Quadrant IV, <b>t</b>angent is positive.</li></ul>
A common mnemonic used to remember these is “All Students Take Calculus.”
Benjamin D. Esham (<a href="//commons.wikimedia.org/wiki/User:Bdesham" title="User:Bdesham">bdesham</a>)
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