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 $${sin}^{\mathrm{2}} {a}+{sin}^{\mathrm{2}} \mathrm{2}{a}+{sin}^{\mathrm{2}}…
Question Number 102783 by bramlex last updated on 11/Jul/20 $$\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 $$\Leftrightarrow\mathrm{6sin2}\theta×\frac{\mathrm{1}}{\mathrm{2}}−\mathrm{6cos2}\theta×\frac{\sqrt{\mathrm{3}}}{\mathrm{2}}−\left(\mathrm{2sin2}\theta×\frac{\sqrt{\mathrm{3}}}{\mathrm{2}}−\mathrm{2cos2}\theta×\frac{\mathrm{1}}{\mathrm{2}}\right)=\mathrm{2}\sqrt{\mathrm{3}}−\mathrm{1} \\…
Question Number 168297 by MdNafiz last updated on 07/Apr/22 $$\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 $${let}\:\frac{\pi}{\mathrm{7}}=\theta \\ $$$$\:\:\therefore{cos}\mathrm{2}\theta+{cos}\mathrm{4}\theta+{cos}\mathrm{8}\theta \\…
Question Number 102705 by dw last updated on 10/Jul/20 $${For}\:{what}\:{values}\:{of}\:{k}\:\left({cosA}−\frac{\mathrm{1}}{\mathrm{5}}\right)\left({cosB}−\frac{\mathrm{1}}{\mathrm{5}}\right)\left({cosC}−\frac{\mathrm{1}}{\mathrm{5}}\right)\leqslant{k} \\ $$$${hold}\:{in}\:{all}\:{triangles}\:{ABC}? \\ $$ Terms of Service Privacy Policy Contact: info@tinkutara.com
Question Number 37155 by ajfour last updated on 09/Jun/18 $$\mathrm{3cos}\:{x}−\mathrm{4sin}\:{x}=\mathrm{tan}\:^{\mathrm{2}} {x} \\ $$$${locate}\:{x}. \\ $$ Commented by behi83417@gmail.com last updated on 09/Jun/18 $${c}={cosx},{s}={sinx} \\ $$$$\mathrm{3}{c}−\mathrm{4}{s}=\frac{{s}^{\mathrm{2}}…
Question Number 102600 by dw last updated on 10/Jul/20 Terms of Service Privacy Policy Contact: info@tinkutara.com
Question Number 102587 by 1549442205 last updated on 10/Jul/20 $$\mathrm{Prove}\:\mathrm{that} \\ $$$$\mathrm{cot7}.\mathrm{5}°=\sqrt{\mathrm{2}}+\sqrt{\mathrm{3}}+\sqrt{\mathrm{4}}+\sqrt{\mathrm{6}} \\ $$ Commented by PRITHWISH SEN 2 last updated on 10/Jul/20 $$\mathrm{a}\:\mathrm{different}\:\mathrm{approach} \\…
Question Number 102390 by Dwaipayan Shikari last updated on 08/Jul/20 $${asin}\theta+{bcos}\theta={c} \\ $$$${acosec}\theta+{bsec}\theta={c} \\ $$$$ \\ $$$${prove}\:{that}\:\:\:\:{sin}\mathrm{2}\theta=\frac{\mathrm{2}{ab}}{{c}^{\mathrm{2}} −{a}^{\mathrm{2}} −{b}^{\mathrm{2}} } \\ $$ Commented by PRITHWISH…
Question Number 102190 by dw last updated on 07/Jul/20 $${Find}\:{the}\:{value}\:{of}\:\:{x}\:\centerdot\centerdot\left[{Trigonometric}\:{Subs}.\right] \\ $$$${x}−\frac{{x}}{\:\sqrt{\mathrm{1}−{x}^{\mathrm{2}} }}=\frac{\mathrm{91}}{\mathrm{60}} \\ $$ Answered by bemath last updated on 07/Jul/20 $$\frac{{x}\left(\sqrt{\mathrm{1}−{x}^{\mathrm{2}} }−\mathrm{1}\right)}{\:\sqrt{\mathrm{1}−{x}^{\mathrm{2}} }}\:=\:\frac{\mathrm{91}}{\mathrm{60}}…
Question Number 102177 by dw last updated on 07/Jul/20 Commented by Rasheed.Sindhi last updated on 07/Jul/20 $${ac}+{bd}=\mathrm{0}\Rightarrow{d}=−\frac{{ac}}{{b}} \\ $$$${c}^{\mathrm{2}} +{d}^{\mathrm{2}} ={c}^{\mathrm{2}} +\left(−\frac{{ac}}{{b}}\right)^{\mathrm{2}} =\mathrm{1} \\ $$$$\:\:\:\:\:\:\:\:\:\:\Rightarrow{b}^{\mathrm{2}}…