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Given-that-7-cos-2-24-sin-2-R-cos-2-where-R-gt-0-and-0-lt-lt-pi-2-find-the-maximum-value-of-14-cos-2-48-sin-cos-

Question Number 153736 by ZiYangLee last updated on 09/Sep/21 $$\mathrm{Given}\:\mathrm{that}\:\mathrm{7}\:\mathrm{cos}\:\mathrm{2}\theta+\mathrm{24}\:\mathrm{sin}^{\mathrm{2}} \theta={R}\:\mathrm{cos}\left(\mathrm{2}\theta−\alpha\right), \\ $$$$\mathrm{where}\:{R}>\mathrm{0}\:\mathrm{and}\:\mathrm{0}<\alpha<\frac{\pi}{\mathrm{2}},\:\mathrm{find}\:\mathrm{the}\:\mathrm{maximum} \\ $$$$\mathrm{value}\:\mathrm{of}\:\mathrm{14}\:\mathrm{cos}^{\mathrm{2}} \theta+\mathrm{48}\:\mathrm{sin}\:\theta\:\mathrm{cos}\:\theta. \\ $$ Answered by mr W last updated on…

Show-that-0-pi-2-1-cos-3-sin-2-d-1-3-

Question Number 153737 by ZiYangLee last updated on 09/Sep/21 $$\mathrm{Show}\:\mathrm{that}\:\int_{\mathrm{0}} ^{\:\frac{\pi}{\mathrm{2}}} \frac{\mathrm{1}}{\left(\mathrm{cos}\:\theta+\:\sqrt{\mathrm{3}}\:\mathrm{sin}\:\theta\right)^{\mathrm{2}} }\:{d}\theta=\:\frac{\mathrm{1}}{\:\sqrt{\mathrm{3}}\:} \\ $$ Answered by puissant last updated on 09/Sep/21 $$=\int_{\mathrm{0}} ^{\frac{\pi}{\mathrm{2}}} \frac{\mathrm{1}}{\left[\mathrm{2}\left(\frac{\mathrm{1}}{\mathrm{2}}{cos}\theta+\frac{\sqrt{\mathrm{3}}}{\mathrm{2}}{sin}\theta\right)\right]^{\mathrm{2}}…

Question-153696

Question Number 153696 by SANOGO last updated on 09/Sep/21 Answered by puissant last updated on 09/Sep/21 $${x}_{{n}} =\underset{{k}=\mathrm{1}} {\overset{{n}} {\sum}}\frac{\mathrm{1}}{{n}^{\mathrm{2}} +{k}} \\ $$$${Calcul}\:{des}\:\mathrm{5}\:{premiers}\:{termes}.. \\ $$$$\rightarrow\:{x}_{\mathrm{1}}…

solve-in-R-x-3-y-3-19-xy-6-

Question Number 153698 by mathocean1 last updated on 09/Sep/21 $${solve}\:{in}\:\mathbb{R} \\ $$$$\begin{cases}{{x}^{\mathrm{3}} −{y}^{\mathrm{3}} =\mathrm{19}}\\{{xy}=\mathrm{6}}\end{cases} \\ $$ Answered by amin96 last updated on 09/Sep/21 $$\left({x}−{y}\right)\left({x}^{\mathrm{2}} +{xy}+{y}^{\mathrm{2}}…

Question-153676

Question Number 153676 by SANOGO last updated on 09/Sep/21 Answered by som(math1967) last updated on 09/Sep/21 $$\mathrm{1}.\:\boldsymbol{{a}}>\mathrm{0},\boldsymbol{{b}}>\mathrm{0} \\ $$$$\:\left(\boldsymbol{{a}}−\boldsymbol{{b}}\right)^{\mathrm{2}} \geqslant\mathrm{0}\:\:\:\left[\boldsymbol{{if}}\:\boldsymbol{{a}}=\boldsymbol{{b}}\:\boldsymbol{{then}}\left(\boldsymbol{{a}}−\boldsymbol{{b}}\right)=\mathrm{0}\right] \\ $$$$\Rightarrow\left(\boldsymbol{{a}}+\boldsymbol{{b}}\right)^{\mathrm{2}} −\mathrm{4}\boldsymbol{{ab}}\geqslant\mathrm{0} \\ $$$$\Rightarrow\:\left(\frac{\boldsymbol{{a}}+\boldsymbol{{b}}}{\mathrm{2}}\right)^{\mathrm{2}}…