Timeline for Geometric meaning of a trigonometric identity
Current License: CC BY-SA 3.0
14 events
| when toggle format | what | by | license | comment | |
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| S Jun 24, 2015 at 16:20 | history | suggested | CommunityBot | CC BY-SA 3.0 |
Corrected two small typo's.
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| Jun 24, 2015 at 16:04 | review | Suggested edits | |||
| S Jun 24, 2015 at 16:20 | |||||
| Aug 4, 2011 at 1:10 | comment | added | Michael Hardy | Oh. I was missing the forest for the trees. | |
| Aug 3, 2011 at 22:28 | comment | added | Noam D. Elkies | @M.Hardy: it's the logarithmic-derivative form of the derivative of a product of $n$ functions. I already evaluated the factor $P(X)$ at $X=1$. | |
| Aug 3, 2011 at 1:04 | comment | added | Michael Hardy | Where does the second equality after $-S$ come from? | |
| Aug 1, 2011 at 0:29 | comment | added | Noam D. Elkies | :-) But this isn't "engineering_overflow". | |
| Aug 1, 2011 at 0:22 | comment | added | Michael Hardy | BTW, if you had left the index as $i$ and let $j$ be the square root of $-1$, that would have been just the notation in which I (as the son of an electrical engineer) first learned about complex numbers. | |
| Jul 31, 2011 at 23:53 | comment | added | Noam D. Elkies | Thanks --- and yes, you're right, those $\cos \alpha_j$'s should have been in the numerator, and the ones coming from $1 + i \tan \alpha_j$ in the denominator!, I corrected this now. | |
| Jul 31, 2011 at 23:51 | history | edited | Noam D. Elkies | CC BY-SA 3.0 |
Put $\cos \alpha_j$ factors in numerator and denominator where they belong, rather than vice versa, correcting error noted by M.Hardy
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| Jul 31, 2011 at 22:53 | comment | added | Michael Hardy | Nice. (Looks to me as if the product of cosines should be in the numerator, so that −S=∏jcosαjReP′(1). I'll finish working through some further details shortly.....) | |
| Jul 31, 2011 at 6:18 | history | edited | Noam D. Elkies | CC BY-SA 3.0 |
inserted \cdot in $i \tan \alpha_j \cdot X$ (twice)
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| Jul 31, 2011 at 3:40 | history | edited | Noam D. Elkies | CC BY-SA 3.0 |
Corrected a sign error in the initial formula for $S$
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| Jul 31, 2011 at 3:01 | history | edited | Noam D. Elkies | CC BY-SA 3.0 |
A bit more copy editing, mostly to highlight and explain the key point $\sum_j \alpha_j = \pi$
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| Jul 31, 2011 at 2:26 | history | answered | Noam D. Elkies | CC BY-SA 3.0 |