--description--

In this video, you will learn about half angle formulas.

--questions--

--text--

What is the half angle formula for $\cos\left(\frac{\theta}{2}\right)$?

--answers--

$\cos\left(\frac{\theta}{2}\right) = \frac{1 + \cos(\theta)}{2}$

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$\cos\left(\frac{\theta}{2}\right) = \pm\sqrt{\frac{1 + \cos(\theta)}{2}}$

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$\cos\left(\frac{\theta}{2}\right) = \pm\sqrt{\frac{1 - \cos(\theta)}{2}}$

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$\cos\left(\frac{\theta}{2}\right) = \sqrt{1 - \cos^2(\theta)}$

--video-solution--

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