# How do you evaluate sine, cosine, tangent of -405^circ without using a calculator?

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#### Explanation

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#### Explanation:

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1
Feb 20, 2018

$\sin \left(- 405\right) = - \left(\frac{1}{\sqrt{2}}\right)$

$\cos \left(- 405\right) = \left(\frac{1}{\sqrt{2}}\right)$

$\tan \left(- 405\right) = - 1$

#### Explanation:

$\sin \left(- 405\right) = \sin \left(- 360 - 45\right) = \sin \left(- 45\right) = - \sin 45 = - \left(\frac{1}{\sqrt{2}}\right)$

$\cos \left(- 405\right) = \cos \left(- 360 - 45\right) = \cos \left(- 45\right) = \cos 45 = \left(\frac{1}{\sqrt{2}}\right)$

$\tan \left(- 405\right) = \tan \left(- 360 - 45\right) = \tan \left(- 45\right) = - \tan 45 = - 1$

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