If $sin x = \frac{2}{4}$ $sinx=2/4$ , how do you find $cos 2 x$ $cos2x$ ?

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Answer 1 · 2016-07-01T16:29:05

$cos 2 x = \frac{1}{2}$ $cos2x=1/2$

We have the identity $cos 2 x = 1 - 2 {sin}^{2} x$ $cos2x=1-2sin^2x$

Hence as $sin x = \frac{2}{4}$ $sinx=2/4$ ,

$cos 2 x = 1 - 2 {sin}^{2} x = 1 - 2 {(\frac{2}{4})}^{2}$ $cos2x=1-2sin^2x=1-2(2/4)^2$

= $1 - \frac{2 \times 2 \times 2}{4 \times 4}$ $1-(2xx2xx2)/(4xx4)$

= $1 - \frac{1}{2} = \frac{1}{2}$ $1-1/2=1/2$

If sinx=24sinx=2/4, how do you find cos2xcos2x?