Sin theta = 24/25, cos theta > 0, Find cos(2theta)

QUESTION POSTED AT 01/06/2020 - 04:15 PM

Answered by admin AT 01/06/2020 - 04:15 PM

Well... you don't necessarily need to get the cosine value, in order to get the double angle

\bf \textit{Double Angle Identities}
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cos(2\theta )=1-2sin^2(\theta )\qquad \qquad  sin(\theta )=\cfrac{24}{25}
cos(2\theta )=1-2\left( \cfrac{24}{25} \right)^2\implies cos(2\theta )=-0.8432
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QUESTION POSTED AT 01/06/2020 - 04:46 PM