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Category: Trigonometry

2-n-1-sin-a-sin-2a-sin-3a-sin-n-1-a-n-why-

Question Number 23243 by paro123 last updated on 27/Oct/17 $$\mathrm{2}^{\mathrm{n}−\mathrm{1}} \mathrm{sin}\:\mathrm{a}×\mathrm{sin}\:\mathrm{2a}×\mathrm{sin}\:\mathrm{3a}×……×\mathrm{sin}\:\left(\mathrm{n}−\mathrm{1}\right)\mathrm{a}=\mathrm{n}\:\mathrm{why}? \\ $$ Commented by mrW1 last updated on 28/Oct/17 $$\mathrm{this}\:\mathrm{statement}\:\mathrm{is}\:\mathrm{wrong}! \\ $$$$ \\ $$$$\mathrm{you}\:\mathrm{can}\:\mathrm{find}\:\mathrm{a}\:\mathrm{lot}\:\mathrm{of}\:\mathrm{examples}:…

The-number-of-solution-s-of-the-equation-x-3-x-2-4x-2sinx-0-in-0-2pi-is-are-

Question Number 23231 by Tinkutara last updated on 27/Oct/17 $$\mathrm{The}\:\mathrm{number}\:\mathrm{of}\:\mathrm{solution}\left(\mathrm{s}\right)\:\mathrm{of}\:\mathrm{the}\:\mathrm{equation} \\ $$$${x}^{\mathrm{3}} \:+\:{x}^{\mathrm{2}} \:+\:\mathrm{4}{x}\:+\:\mathrm{2sin}{x}\:=\:\mathrm{0}\:\mathrm{in}\:\left[\mathrm{0},\:\mathrm{2}\pi\right],\:\mathrm{is}/\mathrm{are} \\ $$ Answered by ajfour last updated on 28/Oct/17 $${One}\:. \\…

Solve-the-equation-for-reals-cos-2-x-1-5-sin-2-x-1-sin-2-x-1-5-cos-2-x-1-5tan-2-x-

Question Number 154216 by EDWIN88 last updated on 15/Sep/21 $${Solve}\:{the}\:{equation}\:{for}\:{reals}\: \\ $$$$\:\frac{\mathrm{cos}\:^{\mathrm{2}} {x}−\frac{\mathrm{1}}{\mathrm{5}}\mathrm{sin}\:^{\mathrm{2}} {x}+\mathrm{1}}{\mathrm{sin}\:^{\mathrm{2}} {x}−\frac{\mathrm{1}}{\mathrm{5}}\mathrm{cos}\:^{\mathrm{2}} {x}+\mathrm{1}}\:=\:\mathrm{5tan}\:^{\mathrm{2}} {x}\: \\ $$ Answered by MJS_new last updated on…

1-cos-pi-11-1-cos-3pi-11-1-cos-5pi-11-1-cos-7pi-11-1-cos-9pi-11-

Question Number 88567 by jagoll last updated on 11/Apr/20 $$\left(\mathrm{1}+\mathrm{cos}\:\frac{\pi}{\mathrm{11}}\right)\left(\mathrm{1}+\mathrm{cos}\:\frac{\mathrm{3}\pi}{\mathrm{11}}\right)\left(\mathrm{1}+\mathrm{cos}\:\frac{\mathrm{5}\pi}{\mathrm{11}}\right)\left(\mathrm{1}+\mathrm{cos}\:\frac{\mathrm{7}\pi}{\mathrm{11}}\right)\left(\mathrm{1}+\mathrm{cos}\:\frac{\mathrm{9}\pi}{\mathrm{11}}\right) \\ $$ Commented by jagoll last updated on 11/Apr/20 $$\mathrm{T}=\:\left(\mathrm{2cos}\:^{\mathrm{2}} \left(\frac{\pi}{\mathrm{22}}\right)\right)\left(\mathrm{2cos}^{\mathrm{2}} \:\left(\frac{\mathrm{3}\pi}{\mathrm{22}}\right)\right)\left(\mathrm{2cos}\:^{\mathrm{2}} \left(\frac{\mathrm{5}\pi}{\mathrm{22}}\right)\right) \\ $$$$\left(\mathrm{2cos}\:^{\mathrm{2}}…