Trig exact values and identities (1 Viewer)

fifibum · Jun 12, 2016

How would you find the exact value of sin 67.5 cos 67.5?
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InteGrand · Jun 12, 2016

fifibum said:
How would you find the exact value of sin 67.5 cos 67.5?
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$\noindent Note that $67.5^\circ$ is half of $135^\circ$, and we know the exact value of $\cos \left(135^\circ\right)$. So we can apply the half-angle identities to find the exact values, noting to take the positive square root since the angles are acute.$

$\noindent The half-angle identities are $\sin^2 \frac{x}{2}=\frac{1}{2}-\frac{1}{2}\cos x$ and $\cos^2 \frac{x}{2}=\frac{1}{2}+\frac{1}{2}\cos x$.$

Trig exact values and identities (1 Viewer)

fifibum

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InteGrand

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