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About Sherry Wallin
Expertise
I can answer most questions up though Calculus and some in Number Theory and Abstract Algebra.

Experience
I have had my Bachelor's Degree since 1987 and have been a teacher since 1988.

Education/Credentials
I have taught 10 years at the community college level, medical college, and technical college as well as a high school instructor and alternative education instructor

 
   

You are here:  Experts > Science > Mathematics > Advanced Math > Trignometry

Advanced Math - Trignometry


Expert: Sherry Wallin - 7/4/2009

Question
How to show dy/dx=((sin2x)/(1-cos2x)) =cotx? Try already using cos2x & sin2x formulae but still can't get it. Please help me. Thanks

Answer
Warm~
    I think the question is written incorrectly because
((sin2x)/(1-cos2x)) = cotx. You can't 'find' dy/dx unless you know what y is either explicitly or implicitly. We can show ((sin2x)/(1-cos2x)) = cotx are equal like so:
Using sin 2x = 2 sinx cosx and cos 2x = 2cos^2x - 1 we have
2 sinx cosx/(2-2cos^2x) = 2 sinx cosx/2(1-cos^2x) = 2 sinx cosx/2sin^2x
= sinx cosx/sin^2 x = cosx/sinx = cotx. Does this make sense?

Math Prof

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