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2m
answered Find the value without using calculator (Trigo)
3h
comment Solve for real value of $x$: $|x^2 -2x -3| > |x^2 +7x -13|$
Means is more important than the end. So, please share your approach.
20h
answered exponent problem solving
23h
comment If $\sin s=-1/3$ and $s$ is in the $4$-th quadrant, find the exact value of $\sin (2s)$
@Ayyyyy, Have you heard of Double Angle formula?
23h
answered If $\sin s=-1/3$ and $s$ is in the $4$-th quadrant, find the exact value of $\sin (2s)$
1d
comment Problem about complex number
@Vishwjit, See math.stackexchange.com/questions/192742/how-to-solve-x3-1
1d
comment If $\sin{x}+\sin{y}+\sin{z}= \cos{x}+\cos{y}+\cos{z}=0$, find the value of $\cos{2x}+\cos{2y}+\cos{2z}$.
$$e^{ix}+e^{iy}+e^{iz}=\cdots=0,e^{-ix}+e^{-iy}+e^{-iz}=\cdots=0$$ and $$2\cos x=e^{ix}+e^{-ix}$$
1d
answered Evaluating the $\displaystyle \lim_{x\to0}\frac{4^x-1}{8^x-1}$ without L'Hospital Rule
2d
comment Suppose $m \mid 2^p - 1$. Show that $m \equiv 1 \pmod {2p}$.
See $\#3$ of en.wikipedia.org/wiki/…
2d
revised Number sequence - arithmetic sequence difference constant - find formula
added 179 characters in body
2d
answered Number sequence - arithmetic sequence difference constant - find formula
2d
answered Roots of a polynomial whose coefficients are ratios of binomial coefficients
2d
comment Prove $\sin \frac{\alpha}{2}\sin \frac{\beta}{2}\sin \frac{\gamma}{2}\leq \frac {1}{8}$, $\alpha, \gamma\, \beta$ being angles of a triangle
@user31415, Please follow my answers here : math.stackexchange.com/questions/443322/… and math.stackexchange.com/questions/472169/…
May
17
comment Roots of a polynomial whose coefficients are ratios of binomial coefficients
Related : math.stackexchange.com/questions/951522/…
May
16
comment Find the value of : $\cos x \cos 2x…\cos 999x$ given that $x=\frac {2\pi}{1999}$
@Shubham, In fact, the coefficient of $\cos^{2n+1}x$ is $$\binom{2n+1}0-\binom{2n+1}2+\cdots=(1+1)^{2n+1-1}$$
May
16
comment Find the value of : $\cos x \cos 2x…\cos 999x$ given that $x=\frac {2\pi}{1999}$
@Shubham, Yes, trans4mind.com/personal_development/mathematics/trigonometry/… and examples : trans4mind.com/personal_development/mathematics/trigonometry/…
May
16
comment Find the value of : $\cos x \cos 2x…\cos 999x$ given that $x=\frac {2\pi}{1999}$
@Henry, Was actually leaving it for the OP to complete. But, now it has been added for better clarity..
May
16
revised Find the value of : $\cos x \cos 2x…\cos 999x$ given that $x=\frac {2\pi}{1999}$
added 72 characters in body
May
16
comment Find the value of : $\cos x \cos 2x…\cos 999x$ given that $x=\frac {2\pi}{1999}$
@Henry, Can you please have a look into the updated post. Sp.c $\implies\prod_{m=1}^{2n}\cos\dfrac{2m\pi}{2n+1}=\left(\prod_{m=1}^n\cos\dfrac{2‌​m\pi}{2n+1}\right)^2$
May
16
revised Find the value of : $\cos x \cos 2x…\cos 999x$ given that $x=\frac {2\pi}{1999}$
added 326 characters in body