Category: Trigonometry

Question Number 129719 by bramlexs22 last updated on 18/Jan/21 $$\cos \left(\pi \sin \left(\frac{\mathrm{x}}{3}\right)\right)=\sin \left(\pi \cos \left(\frac{\mathrm{x}}{3}\right)\right)$$$$\mathrm{x}=?$$$$$$ Answered by liberty last updated on 18/Jan/21 $$\:\mathrm{cos}\:\left(\pi\mathrm{sin}\:\frac{\mathrm{x}}{\mathrm{3}}\right)=\mathrm{cos}\:\left(\frac{\pi}{\mathrm{2}}−\pi\mathrm{cos}\:\frac{\mathrm{x}}{\mathrm{3}}\right) \…

Question Number 64173 by Eminem last updated on 14/Jul/19 $$showtbat\underset{k=1}{\prod ^n}(1-\frac{{sin}^2\left(\frac{\theta }{2n}\right)}{{sin}^2\left(\frac{2k-1}{4}\pi \right)})=cos\left(\theta \right)$$ Commented by Prithwish sen last updated on 15/Jul/19 $$\mathrm{Is}'\mathrm{nt}\:\mathrm{it}\:\mathrm{cos}^{\mathrm{n}}…

Question Number 63747 by Tony Lin last updated on 08/Jul/19 $$Whatdoes{sin}^{-2}xmean?$$ Commented by MJS last updated on 08/Jul/19 $${\mathrm{that}}^{\prime }\mathrm{s}\mathrm{the}\mathrm{question}\dots$$$$\mathrm{we}'\mathrm{re}\:\mathrm{not}\:\mathrm{consequent}\:\mathrm{in}\:\mathrm{these}\:\mathrm{things} \…

Question Number 129234 by bemath last updated on 14/Jan/21 $$\cos {}^{2}47°+{\cos }^{2}73°+\cos 47°\cos 73°+\frac{1}{2}=?$$ Answered by liberty last updated on 14/Jan/21 $${(\cos 73°+\cos 47°)}^2-\cos 73°\cos 47°+\frac{1}{2}=$$$$\left(\mathrm{2cos}\:\mathrm{60}°\mathrm{cos}\:\mathrm{13}°\right)^{\mathrm{2}}…

Question Number 129231 by liberty last updated on 14/Jan/21 $$\mathrm{Given}\{\begin{array}{l}a=\sin x+\sin 2x\\ b=\cos x+\cos 2x\end{array}.\mathrm{If}(a^2+b^2)(a^2+b^2-3)=\cos 2x+3\cos x$$$$\mathrm{then}x=?$$ Answered by MJS_new last updated on 14/Jan/21…