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How do you prove that tan(-x) = -tanx
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High School Teacher
To prove, express the left side with its equivalent positive angle.
Then, apply the identity of difference of two angles for tangent.
Since `tan 2pi=0` , left side simplifies to :
`-tanx =- tanx`
Since the left side simplifies to -tanx and this proves that tan(-x) is equal to -tanx.
Posted by mjripalda on July 30, 2013 at 1:10 AM (Answer #1)
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