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| Math Central | Quandaries & Queries |
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Question from Student, a student: verify cos(2x)=(cot(x)-tan(x))/(cot(x)+tan(x)) |
Hi,
I multiplied both sides by cot(x) + tan(x), wrote tan(x) and cot(x) in terms of sin(x) and cos(x) and wrote cos(2x) = cos2(x) - sin2(x). This gave me
[cos2(x) - sin2(x)][cos(x)/sin(x) + sin(x)/cos(x)] = cos(x)/sin(x) - sin(x)/cos(x).
Find a common denominator for the right side and the left side and simplify.
Penny
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