Is this equation an identity? tanx=sinx/cos x
2 answers:
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Answer:
see below
Step-by-step explanation:
Put -1 where x is in each expression and evaluate it.
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You will find that the expression is zero when the numerator is zero. And you will find the numerator is zero when it has a factor that is equivalent to ...
(x +1)
Substituting x=-1 into this factor makes it be ...
(-1 +1) = 0
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Evaluating the first expression, we have ...
This first expression is one you want to "check."
You can see that the reason the expression is zero is that x+1 has a sum of zero. You can look for that same sum in the other expressions. (The tricky one is the one with the factor (x -(-1)). You know, of course, that -(-1) = +1.)
