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# How do I find the value of sin (5Pi/4)?

Sep 24, 2015

Find $\sin \left(\frac{5 \pi}{4}\right)$
Ans: $- \frac{\sqrt{2}}{2}$
$\sin \left(\frac{5 \pi}{4}\right) = - \sin \left(\frac{\pi}{4}\right)$
Trig Table of Special Arcs gives --> $\sin \left(\frac{\pi}{4}\right) = \frac{\sqrt{2}}{2}$, therefor:
$\sin \left(\frac{5 \pi}{4}\right) = - \frac{\sqrt{2}}{2}$