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 Feb 24 reviewed Approve Indefinite Integral $\int \sin (x) \ln (\tan (x))dx$ Feb 24 answered Solving $\int\sqrt{1+(-2ax+b)^2}\;dx$ Feb 20 answered $\lim_{(x,y) \to(0,0)}\sin(x - y)$ Feb 12 awarded Notable Question Feb 9 reviewed Approve Is there a method to memorizing $\pi$? Feb 9 answered How to solve $L = (1.463 \cdot 10^7R^2)/(F^2V) - 1.463R$ for $R$? Feb 6 comment For which constants does the following converge to a delta function? Depending on your definition of a delta function this may not be possible, since the integral of your function over $\mathbb{R}^2$ doesn't converge for any $n$, no matter what $c_n$ is. As far as I know, the delta function must verify $\int_\mathbb{R} \delta(x)\ dx = 1$. Feb 5 answered Evaluating $\int \frac{1}{\sqrt{x^2 + a^2}}\, dx$ without resorting to trigonometric $u$-substitution Feb 5 comment Evaluating $\int \frac{1}{\sqrt{x^2 + a^2}}\, dx$ without resorting to trigonometric $u$-substitution Would you accept hyperbolic functions? :) Jan 27 revised Find limit when $\theta$ tends to $0$ of $\tan(\theta) /\theta$ added 10 characters in body Jan 7 answered Indefinite integral question. Jan 6 reviewed Approve How to form a differential equation, given temperature and direction of heat flow Jan 5 reviewed Reject Prove that $4$ is the only solution to $2+2$. Jan 4 revised Graphs of functions with fractional powers: $x^{p/q}$ edited tags Jan 1 comment Is this a solution to the indefinite integral of $e^{-x^2}$? This is a nice idea, but I'm sorry to tell you that there's proof that there is no elementary formula for the integral. If you're okay with a series, just expand $e^{-x^2}$ and integrate term by term. Dec 30 accepted Doubts with differential geometry notation in Frankel Dec 28 asked Doubts with differential geometry notation in Frankel Dec 13 comment Can integration get the real value of $\pi$? @user3015600: You could, in principle, get $\pi$ with infinite precision. If you want any digit of the decimal expansion of $\pi$, there's a zillion formulas that you can use to get it. The problem is that we can never know all of them, not because math doesn't work, but simply because there's infinitely many of them and we don't have infinite time. Dec 13 answered Can integration get the real value of $\pi$? Dec 10 comment Explain complex numbers Also, I think this is a duplicate: math.stackexchange.com/questions/251665/…