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  • 0 posts edited
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  • 31 votes cast
Aug
27
revised How can I describe the area between two ellipses?
Resolved one of my questions, formatting
Aug
27
comment How can I describe the area between two ellipses?
FYI - The image I posted used (1) $\frac{(x-5)^2}{3^2}+\frac{y^2}{6^2}=1$ and (2) $\frac{(x-7)^2}{12}+\frac{y^2}{3^2}$. Should I put that in there?
Aug
27
comment How can I describe the area between two ellipses?
@BenCrowell I agree with Lubin - most likely, the term $(1-\frac{(x_0-c_2)^2}{x_1^2})$ in $y_0=\sqrt{y_2^2(1-\frac{(x_0-c_2)^2}{x_1^2})}$ becomes negative, causing the smaller $x$ values to become imaginary. Therefore, the $x$ that we're looking at has to be the larger one. I guess that answers that. I don't think we need to go through a numerical case if my explanation sounds convincing enough. That still only gets me down to where I ended in my question, though.
Aug
27
asked How can I describe the area between two ellipses?
Aug
26
comment Numerical Analysis
There was no complex conjugate. Just saying.
Aug
26
answered Can you approximate a vector field?
Aug
26
revised Calculate the area on a sphere of the intersection of two spherical caps
added 173 characters in body
Aug
26
revised Calculate the area on a sphere of the intersection of two spherical caps
Minor LaTeX corrections, grammar
Aug
26
revised Calculate the area on a sphere of the intersection of two spherical caps
Minor LaTeX corrections
Aug
26
answered Calculate the area on a sphere of the intersection of two spherical caps
Aug
25
comment Divisibility of consecutive natural numbers
@dato yes but what anon is trying to convey here is that there doesn't have to be a prime every 2012 consecutive numbers.
Aug
25
accepted Solving the DE for a two-body system
Aug
24
comment Pre-Calculus - Solving for $x^3$
When you used the quadratic formula and got the two roots $a=\frac{-1+i\sqrt{3}}{2}$ and $b=\frac{-1-i\sqrt{3}}{2}$ you should be replacing $x^2+x+1$ with $(x-a)(x-b)$, not what you did.
Aug
24
revised Green's theorem for conservative fields - are partials equal?
Minor math error (forgot dA)
Aug
24
comment Green's theorem for conservative fields - are partials equal?
No problem. Glad to help. FYI, subscripts, in this context, mean partials - $\frac{\partial f}{\partial x}=f_x$.
Aug
24
comment Integer combination
Will the formula always be less than or equal to? And that simple? (i.e., in the form $a x + b y \le c$ for integers a, b, and c)?
Aug
24
comment Green's theorem for conservative fields - are partials equal?
There. I hope my edit was what you were looking for.
Aug
24
revised Green's theorem for conservative fields - are partials equal?
Missed a period, added a proof, put more LaTeX in.
Aug
24
comment Green's theorem for conservative fields - are partials equal?
@alkamid $P_y$ and $f_{xy}$ are the same thing (if $f$ exists). The actual Young's Theorem says $f_{xy}=f{yx}$. As for the typo, it was just a missing period, right?
Aug
24
revised Green's theorem for conservative fields - are partials equal?
Missed a period.