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About Socrates
Expertise
I can answer any questions from the standard four semester Calulus sequence. Derivatives, partial derivatives, chain rule, single and multiple integrals, change of variable, sequences and series, vector integration (Green`s Theorem, Stokes, and Gauss) and applications. Pre-Calculus, Linear Algebra and Finite Math questions are also welcome.

Experience
Ph.D. in Mathematics and many years teaching undergraduate courses at three state universities.

Education/Credentials
B.S. , M.S. , Ph.D.

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Advanced Math - Precalculus

Expert: Socrates - 7/22/2009

Question
1+sec A/sec A = sin^2/1-cos A establish an identity...i
got all the work, but some where im doing something wrong
Here is my work:

1+1/cos A / 1/cos A

cos A +1/cos A/1/cos A

then i bring up the bottom to the top and i end up with
cos A +1 ? please help, thank you !!

Answer
Your work is correct as far as it goes.

The left side is cos A + 1 , as you have found .

But the right side is sin^2/1-cos A = (1 - cos^2 A )/ (1 - cos A )

Factor the numerator (1 - cos^2 A ) = (1 - cos A )(1 + cos A )

so sin^2/1-cos A = (1 - cos A )(1 + cos A )/ (1 - cos A ) = 1 + cos A

Which is the same as the left side.

If you prefer , you can just keep working with the left side

cos A + 1 = (1 + cos A )/ 1 = (1 - cos A )(1 + cos A )/ (1 - cos A ) =

(1 - cos^2 A )/ (1 - cos A ) = sin^2/(1-cos A)

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