Question Number 165851 by Bagus1003 last updated on 09/Feb/22
$$\mathrm{2}\left(\mathrm{cos}\left(\mathrm{45}\right)\right)^{\mathrm{4}} \:=\:\frac{\mathrm{1}}{\mathrm{2}}\:Ă\:\frac{\boldsymbol{\tau}}{{x}\:Ă\:\mathrm{2}}\:+\:\mathrm{1}\:â\:\frac{\mathrm{2}}{\mathrm{2}} \\ $$$${How}\:{much}\:{the}\:{x}\:{is}? \\ $$
Answered by MJS_new last updated on 09/Feb/22
$$\mathrm{2}\left(\mathrm{cos}\left(\mathrm{45}\right)\right)^{\mathrm{4}} \:=\frac{\mathrm{1}}{\mathrm{2}}Ă\frac{\tau}{{x}Ă\mathrm{2}}+\mathrm{1}â\frac{\mathrm{2}}{\mathrm{2}} \\ $$$$\mathrm{2}\left(\mathrm{cos}\left(\mathrm{45}\right)\right)^{\mathrm{4}} â\mathrm{1}+\frac{\mathrm{2}}{\mathrm{2}}\:=\frac{\mathrm{1}}{\mathrm{2}}Ă\frac{\tau}{{x}Ă\mathrm{2}} \\ $$$$\left(\mathrm{2}\left(\mathrm{cos}\left(\mathrm{45}\right)\right)^{\mathrm{4}} â\mathrm{1}+\frac{\mathrm{2}}{\mathrm{2}}\:\right)\boldsymbol{\div}\frac{\mathrm{1}}{\mathrm{2}}=\frac{\tau}{{x}Ă\mathrm{2}} \\ $$$$\frac{\left(\mathrm{2}\left(\mathrm{cos}\left(\mathrm{45}\right)\right)^{\mathrm{4}} â\mathrm{1}+\frac{\mathrm{2}}{\mathrm{2}}\:\right)\boldsymbol{\div}\frac{\mathrm{1}}{\mathrm{2}}}{\tau}=\frac{\mathrm{1}}{{x}Ă\mathrm{2}} \\ $$$${x}Ă\mathrm{2}Ă\frac{\left(\mathrm{2}\left(\mathrm{cos}\left(\mathrm{45}\right)\right)^{\mathrm{4}} â\mathrm{1}+\frac{\mathrm{2}}{\mathrm{2}}\:\right)\boldsymbol{\div}\frac{\mathrm{1}}{\mathrm{2}}}{\tau}=\mathrm{1} \\ $$$${x}=\frac{\mathrm{1}}{\mathrm{2}Ă\frac{\left(\mathrm{2}\left(\mathrm{cos}\left(\mathrm{45}\right)\right)^{\mathrm{4}} â\mathrm{1}+\frac{\mathrm{2}}{\mathrm{2}}\:\right)\boldsymbol{\div}\frac{\mathrm{1}}{\mathrm{2}}}{\tau}} \\ $$
Answered by Bagus1003 last updated on 09/Feb/22
$$\mathrm{cos}\left(\mathrm{45}\right)=\frac{\sqrt{\mathrm{2}}}{\mathrm{2}} \\ $$$$\left(\frac{\sqrt{\mathrm{2}}}{\mathrm{2}}\right)^{\mathrm{2}} =\frac{\mathrm{2}}{\mathrm{4}}=\frac{\mathrm{1}}{\mathrm{2}} \\ $$$$\left(\frac{\mathrm{1}}{\mathrm{2}}\right)^{\mathrm{2}} =\frac{\mathrm{1}}{\mathrm{4}} \\ $$$$\left(\frac{\sqrt{\mathrm{2}}}{\mathrm{2}}\right)^{\mathrm{4}} =\frac{\mathrm{1}}{\mathrm{4}} \\ $$$$\mathrm{2}Ă\frac{\mathrm{1}}{\mathrm{4}}=\frac{\mathrm{1}}{\mathrm{2}} \\ $$$$\frac{\mathrm{1}}{\mathrm{2}}=\frac{\mathrm{1}}{\mathrm{2}}Ă\frac{\tau}{{x}Ă\mathrm{2}}+\mathrm{1}â\frac{\mathrm{2}}{\mathrm{2}} \\ $$$$\mathrm{0}.\mathrm{5}=\mathrm{0}.\mathrm{5}Ă\frac{\tau}{{x}Ă\mathrm{2}} \\ $$$$\mathrm{0}.\mathrm{5}/\mathrm{0}.\mathrm{5}=\mathrm{1} \\ $$$${Substitute}\:{them} \\ $$$$\mathrm{1}=\frac{\tau}{{x}Ă\mathrm{2}} \\ $$$$\tau=\mathrm{2}\pi \\ $$$$\mathrm{1}=\frac{\mathrm{2}\pi}{{x}Ă\mathrm{2}} \\ $$$$\left({x}Ă\mathrm{2}\right)\mathrm{1}=\frac{\mathrm{2}\pi}{{x}Ă\mathrm{2}}Ă\left({x}Ă\mathrm{2}\right) \\ $$$${x}Ă\mathrm{2}=\mathrm{2}Ă\pi \\ $$$$\mathrm{2}/{x}Ă\mathrm{2}=\mathrm{2}Ă\pi/\mathrm{2} \\ $$$$\mathrm{2}/\mathrm{2}=\mathrm{1} \\ $$$${The}\:{result}\:{of}\:{x}\:{is} \\ $$$${x}=\mathrm{3}.\mathrm{14}..=\pi \\ $$
Commented by MJS_new last updated on 09/Feb/22
$$\mathrm{LOL}!\:\mathrm{Thank}\:\mathrm{you}\:\mathrm{for}\:\mathrm{making}\:\mathrm{it}\:\mathrm{clear}! \\ $$
Commented by Bagus1003 last updated on 09/Feb/22
$${No}\:{problem}\:{dude} \\ $$