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Jul
27
answered Establishing the identity
Jul
27
comment Divisibility for 7
See also: math.stackexchange.com/questions/328562/…
Jul
26
comment Calculus - Limit calculate help
@JaVaPG, $$\lim_{h\to0}\frac hh=1$$ as $h\ne0$ as $h\to0$
Jul
26
comment Even number being express as $4q$ or $4q+2$
You can as $$n\equiv0,2,\cdots,2m-4,2m-2\pmod{2m}$$
Jul
26
comment Calculus - Limit calculate help
@JaVaPG, $$\tan x-1=\frac{\sin x}{\cos x}-1=?$$
Jul
26
comment Even number being express as $4q$ or $4q+2$
Is $5$ even number?
Jul
26
comment Calculus - Limit calculate help
@JaVaPG,Please find the edited version
Jul
26
revised Calculus - Limit calculate help
added 214 characters in body
Jul
26
answered Calculus - Limit calculate help
Jul
26
answered Prove that $16 \cos 12^\circ ·\cos 24^\circ ·\cos 48^\circ· \cos 96^\circ ·\cos 192^\circ = 1$
Jul
26
answered Prove that $16 \cos 12^\circ ·\cos 24^\circ ·\cos 48^\circ· \cos 96^\circ ·\cos 192^\circ = 1$
Jul
26
answered Find limit of fraction without derivatives
Jul
26
comment Evaluating the alternating series $\sum_{n = 1}^\infty \frac {(-1)^{n-1}}{3^{n-1}}$
@LeoMatyushkin, See also : en.wikipedia.org/wiki/Geometric_series#Proof_of_convergence
Jul
26
comment Evaluating the alternating series $\sum_{n = 1}^\infty \frac {(-1)^{n-1}}{3^{n-1}}$
@LeoMatyushkin, Definitely. Hope you understand the start index does not matter
Jul
26
answered Evaluating the alternating series $\sum_{n = 1}^\infty \frac {(-1)^{n-1}}{3^{n-1}}$
Jul
26
comment Formulas related to acceleration
school-for-champions.com/science/…
Jul
26
answered Formulas related to acceleration
Jul
26
comment prove $a^2_o-a^2_1+a^2_2-…+(-1)^{n-1}a^2_{n-1}=\frac {1}{2}(a_n+(-1)^{n+1}a^2_n)$
I think, $$0\le k\le 2n$$
Jul
26
comment Prove that $\sin(12^\circ)\sin(48^\circ)\sin(54^\circ)=\frac18$
@Kanishk, Proof is here(cut-the-knot.org/arithmetic/algebra/sin3x.shtml). Also related : math.stackexchange.com/questions/503575/…
Jul
26
comment Prove that $\sin(12^\circ)\sin(48^\circ)\sin(54^\circ)=\frac18$
@Tunk-Fey, $$(3)\implies\cos36^\circ-\cos72^\circ=\frac12$$ (math.stackexchange.com/questions/827540/…)