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comment Deriving the Surface Area of a Spherical Triangle
There is a nice proof at math.rice.edu/~pcmi/sphere/gos4.html
Jan
19
awarded  Custodian
Jan
19
reviewed Reviewed Pricing a riskless asset in the Black & Scholes market
Dec
29
awarded  Yearling
Dec
19
awarded  Constituent
Dec
17
comment Derivation: How do I derivate this
Perhaps FullSimplify[SeriesCoefficient[Exp[-y^2], {y, x, n}] n!, Element[n, Integers] && n > 0] (from V. Reshetnikov) or D[F[n][x] Exp[-x^2], x] // Factor is a better hint. But your question seems to be about mathematics, not the technical software Mathematica
Dec
8
awarded  Caucus
Oct
21
comment Notation for sum of products
Is this a question about standard mathematical notation or about how to write code in the software system Mathematica to represent such a sum?
Sep
20
revised Calculating a limit in two variables by going to polar coordinates.
Fixed typo
Sep
20
comment Calculating a limit in two variables by going to polar coordinates.
@Timbuc Yes, thanks!
Sep
18
answered How to find the intersection points of two circles in 3D
Aug
18
answered Log concavity of binomial coefficients: $ \binom{n}{k}^2 \geq \binom{n}{k-1}\binom{n}{k+1} $
Aug
4
comment Negative number modular positive number ?
This question appears to be off-topic because it is about a different programming language than Mathematica or about mathematics. If it about how Mathematica defines the function Mod (not MOD), then why write %?
Jul
26
comment Intuition on the curl formula
@LucasZanella Maxwell observed that the observed properties of the electromagnetic field were similar to the dynamics of rotating fluids in small cells. The book Maxwell on the Electromagnetic Field: A Guided Study contains excerpts that describe how he deduced his equations. Too long to cover the details in a comment, really.
Jul
5
comment Calculating a limit in two variables by going to polar coordinates.
@Crumbs Given: In polar coordinates, $f(x,y) = r \cdot [\cos\theta \sin^2\theta /(\cos^2\theta + r^2\sin^4\theta)]$, $\theta$ fixed, $r \ne 0$, $r \rightarrow 0$. Hence: If $\cos\theta = 0$, then the second factor equals $0$ for all $r$ (given $r \ne 0$); if $\cos\theta \ne 0$, then the limit of the second factor is $\sin^2\theta/\cos\theta$. In both cases the limit of the second factor exists. The first factor approaches $0$, so the limit is $0$.
Jun
6
comment Is there a difference for discount per unit and discount per purchase total?
This question appears to be off-topic because it is not about Mathematica
Apr
29
revised Calculating a limit in two variables by going to polar coordinates.
Responded to downvote
Apr
19
answered If there are obvious things, why should we prove them?
Apr
1
comment How do you find the general solution to a higher order nonhomogeneous differential equation?
Is this a question about the software product Mathematica?
Mar
15
comment Why are the axes in coordinate geometry perperndicular?
It may be of interest to note that Descartes did not use perpendicular axes in his Geometry. He used distances to given lines, the given lines being at whatever angles and sometimes more than two in number. So having coordinate axes at angles other than 90 degrees came first. Descartes used his method to solve a problem of Pappus that the ancients Greeks could not, and thus proved a new theorem.