If cosA=cos B, then when does A=B? (Always, sometimes, never, infinite etc).

(Evilgrin)

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- Feb 4th 2010, 06:38 AMceroseven"simple" math question
If cosA=cos B, then when does A=B? (Always, sometimes, never, infinite etc).

(Evilgrin) - Feb 4th 2010, 06:51 AMfelper
No. Counterexample:

If you work on the interval , then - Feb 4th 2010, 11:17 AMceroseven
So what is the answer.. Never or sometimes?

- Feb 4th 2010, 12:09 PMbigwave
it is always the same when it is a sign identity

since would just be a reflection of off the x axis then

example: