Menu Close

Category: Trigonometry

8cos-x-8sin-x-3-55tan-x-55-tan-x-

Question Number 168664 by cortano1 last updated on 15/Apr/22 $$\:\:\:\:\:\begin{cases}{\mathrm{8cos}\:{x}−\mathrm{8sin}\:{x}=\mathrm{3}}\\{\mathrm{55tan}\:{x}+\frac{\mathrm{55}}{\mathrm{tan}\:{x}}\:=?}\end{cases} \\ $$ Answered by greogoury55 last updated on 15/Apr/22 $$\:\left(\mathrm{8cos}\:{x}−\mathrm{8sin}\:{x}\right)^{\mathrm{2}} \:=\:\mathrm{9} \\ $$$$\:\mathrm{64}−\mathrm{64sin}\:\mathrm{2}{x}\:=\:\mathrm{9} \\ $$$$\Rightarrow\mathrm{55}\:=\:\mathrm{64sin}\:\mathrm{2}{x}…

Question-168643

Question Number 168643 by BagusSetyoWibowo last updated on 15/Apr/22 Commented by som(math1967) last updated on 15/Apr/22 $$\boldsymbol{{x}}.\boldsymbol{{y}}=\mathrm{10}\:\boldsymbol{{if}}\:\:\boldsymbol{{triangle}}\:\boldsymbol{{is}}\:\boldsymbol{{rt}}.\boldsymbol{{angle}} \\ $$ Commented by safojontoshtemirov last updated on…

cos-2-10-sin-2-25-cos-2-15-sin-2-10-sin-2-25-sin-2-15-

Question Number 168605 by cortano1 last updated on 14/Apr/22 $$\:\:\:\:\:\frac{\mathrm{cos}\:^{\mathrm{2}} \mathrm{10}°+\mathrm{sin}\:^{\mathrm{2}} \mathrm{25}°−\mathrm{cos}\:^{\mathrm{2}} \mathrm{15}°}{\mathrm{sin}\:^{\mathrm{2}} \mathrm{10}°+\mathrm{sin}\:^{\mathrm{2}} \mathrm{25}°−\mathrm{sin}\:^{\mathrm{2}} \mathrm{15}°}=? \\ $$ Commented by som(math1967) last updated on 14/Apr/22…

Question-103021

Question Number 103021 by dw last updated on 12/Jul/20 Answered by Dwaipayan Shikari last updated on 12/Jul/20 $${sinxcos}\frac{{x}}{\mathrm{4}}−\mathrm{2}{sin}^{\mathrm{2}} {x}+{cosx}+{sin}\frac{{x}}{\mathrm{4}}{cosx}−\mathrm{2}{cos}^{\mathrm{2}} {x}=\mathrm{0} \\ $$$${sin}\frac{\mathrm{5}{x}}{\mathrm{4}}+{cosx}=\mathrm{2} \\ $$$${sin}\frac{\mathrm{5}{x}}{\mathrm{4}}+{sin}\left(\frac{\pi}{\mathrm{2}}−{x}\right)=\mathrm{2} \\…

sin-2-pi-11-sin-2-2pi-11-sin-2-5pi-11-

Question Number 37244 by subhendubera201314@gmail.com last updated on 11/Jun/18 $$\mathrm{sin}^{\mathrm{2}} \left(\pi/\mathrm{11}\right)+\mathrm{sin}^{\mathrm{2}} \left(\mathrm{2}\pi/\mathrm{11}\right)+…+\mathrm{sin}^{\mathrm{2}} \left(\mathrm{5}\pi/\mathrm{11}\right)=? \\ $$ Answered by tanmay.chaudhury50@gmail.com last updated on 11/Jun/18 $${sin}^{\mathrm{2}} {a}+{sin}^{\mathrm{2}} \mathrm{2}{a}+{sin}^{\mathrm{2}}…

2-3-1-6sin-2-60-o-2sin-2-30-o-

Question Number 102783 by bramlex last updated on 11/Jul/20 $$\mathrm{2}\sqrt{\mathrm{3}}−\mathrm{1}\:=\:\mathrm{6sin}\:\left(\mathrm{2}\theta−\mathrm{60}^{\mathrm{o}} \right)−\mathrm{2sin} \\ $$$$\left(\mathrm{2}\theta−\mathrm{30}^{\mathrm{o}} \right)\:\Rightarrow\theta=? \\ $$ Answered by 1549442205 last updated on 11/Jul/20 $$\Leftrightarrow\mathrm{6sin2}\theta×\frac{\mathrm{1}}{\mathrm{2}}−\mathrm{6cos2}\theta×\frac{\sqrt{\mathrm{3}}}{\mathrm{2}}−\left(\mathrm{2sin2}\theta×\frac{\sqrt{\mathrm{3}}}{\mathrm{2}}−\mathrm{2cos2}\theta×\frac{\mathrm{1}}{\mathrm{2}}\right)=\mathrm{2}\sqrt{\mathrm{3}}−\mathrm{1} \\…

prove-that-cos-2-7-cos-4-7-cos-8-7-1-2-

Question Number 168297 by MdNafiz last updated on 07/Apr/22 $$\mathrm{prove}\:\mathrm{that}…….. \\ $$$$\mathrm{cos}\:\frac{\mathrm{2}\Pi}{\mathrm{7}}+\mathrm{cos}\:\frac{\mathrm{4}\Pi}{\mathrm{7}}+\mathrm{cos}\:\frac{\mathrm{8}\Pi}{\mathrm{7}}=−\frac{\mathrm{1}}{\mathrm{2}} \\ $$ Answered by som(math1967) last updated on 07/Apr/22 $${let}\:\frac{\pi}{\mathrm{7}}=\theta \\ $$$$\:\:\therefore{cos}\mathrm{2}\theta+{cos}\mathrm{4}\theta+{cos}\mathrm{8}\theta \\…