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Question-185422

Question Number 185422 by Ml last updated on 21/Jan/23 Answered by hmr last updated on 21/Jan/23 $$\mathrm{2}\sqrt{\mathrm{5}}\:=\:\sqrt{\mathrm{20}}\:=\:\left(\mathrm{20}\right)^{\frac{\mathrm{1}}{\mathrm{2}}} \\ $$$$\rightarrow{a}=\:\sqrt[{\mathrm{5}}]{\mathrm{2}\sqrt{\mathrm{5}}}\:=\:\sqrt[{\mathrm{5}}]{\left(\mathrm{20}\right)^{\frac{\mathrm{1}}{\mathrm{2}}} }\:=\:\left(\mathrm{20}\right)^{\frac{\mathrm{1}}{\mathrm{10}}} \\ $$$$ \\ $$$$\sqrt[{\mathrm{3}}]{{a}^{\mathrm{16}} }\:=\:{a}^{\frac{\mathrm{16}}{\mathrm{3}}}…

Prove-that-sin-x-cos-2-x-sin-3-x-cos-4-x-sin-5-x-cos-6-x-sin-7-x-cos-8-x-2-1-

Question Number 119839 by ZiYangLee last updated on 27/Oct/20 $$\mathrm{Prove}\:\mathrm{that} \\ $$$$\mathrm{sin}\:{x}−\mathrm{cos}^{\mathrm{2}} {x}+\mathrm{sin}^{\mathrm{3}} {x}−\mathrm{cos}^{\mathrm{4}} {x}+\mathrm{sin}^{\mathrm{5}} {x}−\mathrm{cos}^{\mathrm{6}} {x} \\ $$$$+\mathrm{sin}^{\mathrm{7}} {x}−\mathrm{cos}^{\mathrm{8}} {x}+\ldots\ldots=\sqrt{\mathrm{2}}−\mathrm{1} \\ $$ Answered by…