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## anonymous 5 years ago Using the first three terms of the Maclaurin's series, what is the value of cos(π/2)?

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1. anonymous

Do you know how to find the MacLaurin/Taylor series of cos(x)?

2. anonymous

No!!

3. anonymous

Here's the general form: MacLaurin series of f(x) centered about x=0: $f(0) + f'(0)*x + \frac{f''(0)*x^2}{2!} + \frac{f'''(0)*x^3}{3!} + ... + \frac{f^n(0)*x^n}{n!} + ...$ Use this to find the MacLaurin series of cos(x). You should notice a pattern pretty quickly, and since you're only using the first three terms, you want to plug π/2 for x after you get the series.

4. anonymous

Thank you !!

5. anonymous

Sorry, the general term should be f^(n) instead of f^n, because you're taking the n-th derivative of the function at 0. No problem. :)

6. anonymous

O.K.

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