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Cos x plus sin x equals 0?

Updated: 4/28/2022
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14y ago

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cosx + sinx = 0 when sinx = -cosx.

By dividing both sides by cosx you get:

sinx/cosx = -1

tanx = -1

The values where tanx = -1 are 3pi/4, 7pi/4, etc.

Those are equivalent to 135 degrees, 315 degrees, etc.

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