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9:04 AM
1
Q: Expanding $\sin(ab)$ in terms of $\sin a$ and $\sin b$.

GwenMotivation behind the question: I've wondered since grade 10 that if $\sin(a+b),\sin(a-b)$ have formulas in terms of $\sin(a)$ and $\sin(b)$, then why not $\sin(ab)$. But I couldn't find any such information sadly. My attempt:- $$\sin(ab)=\sin\bigg(\frac{(a+b)^2}{4}-\frac{(a-b)^2}{4}\bigg)$$ This...

I think it is redundant to have separate tags for individual trigonometric functions - I have edited the tags on that question.
1
Q: Expanding $\sin(ab)$ in terms of $\sin a$ and $\sin b$.

GwenMotivation behind the question: I've wondered since grade 10 that if $\sin(a+b),\sin(a-b)$ have formulas in terms of $\sin(a)$ and $\sin(b)$, then why not $\sin(ab)$. But I couldn't find any such information sadly. My attempt:- $$\sin(ab)=\sin\bigg(\frac{(a+b)^2}{4}-\frac{(a-b)^2}{4}\bigg)$$ This...

I have added to one of the linked questions math.stackexchange.com/q/2425938 - but I have some doubts about the other tags used there.
2
Q: What will be a reason why $\sin(xy)$ and $\sin(x/y)$ have no identities in form of separated functions of $x$ and $y$?

UnavailableWhat I am looking for is, for example, $\sin(xy)=f(x)g(y)$, where $f$ and $y$ are some functions for $x$ and $y$. It is "trivial" to see the answer is no, but not really able to come up with a reasonable reason.

 
 
2 hours later…
11:14 AM
In mathematics, a conformal map is a function that locally preserves angles, but not necessarily lengths. More formally, let U {\displaystyle U} and V {\displaystyle V} be open subsets of R n {\displaystyle \mathbb {R} ^{n}} . A function f : U → V {\displaystyle f:U\to V} is called conformal (or angle-preserving) at...
In mathematics, conformal geometry is the study of the set of angle-preserving (conformal) transformations on a space. In a real two dimensional space, conformal geometry is precisely the geometry of Riemann surfaces. In space higher than two dimensions, conformal geometry may refer either to the study of conformal transformations of what are called "flat spaces" (such as Euclidean spaces or spheres), or to the study of conformal manifolds which are Riemannian or pseudo-Riemannian manifolds with a class of metrics that are defined up to scale. Study of the flat structures is sometimes termed Möbius...
The synonym mentioned above was created by Willie Wong in June 2012: data.stackexchange.com/math/query/1178483/…
 
 
2 hours later…
1:13 PM
0
Q: Freitag and Busam Complex analysis conformal map condition theorem

user760Theorem I.5.15 of the book (Freitag&Busam complex analysis) says: A map $f:D\to D'$, where $D,D'$ open in $\mathbb{C}$, is locally conformal if and only if it is analytic and its derivative is analytic and does not vanish anywhere. At this point in the book, Cauchy integral theorem or CIF haven't...

 

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