Question Number 19097 by Tinkutara last updated on 04/Aug/17 $$\mathrm{If}\:\mathrm{tan}\:\left(\frac{\pi}{\mathrm{4}}\:+\:{x}\right)\:=\:\mathrm{tan}^{\mathrm{3}} \:\left(\frac{\pi}{\mathrm{4}}\:+\:\alpha\right)\:\mathrm{then} \\ $$$$\mathrm{prove}\:\mathrm{that}\:\mathrm{cosec}\:\mathrm{2}{x}\:=\:\frac{\mathrm{1}\:+\:\mathrm{3}\:\mathrm{sin}^{\mathrm{2}} \:\mathrm{2}\alpha}{\mathrm{3}\:\mathrm{sin}\:\mathrm{2}\alpha\:+\:\mathrm{sin}^{\mathrm{3}} \:\mathrm{2}\alpha} \\ $$ Answered by 951172235v last updated on 01/Feb/19 $$\frac{\mathrm{cos}\:\mathrm{x}+\mathrm{sin}\:\mathrm{x}}{\mathrm{cos}\:\mathrm{x}−\mathrm{sin}\:\mathrm{x}}\:\:=\:\:\left(\frac{\mathrm{cos}\:\alpha+\mathrm{sin}\:\alpha}{\mathrm{cos}\:\alpha−\mathrm{sin}\:\alpha}\right)^{\mathrm{3}}…
Question Number 19055 by Tinkutara last updated on 03/Aug/17 $$\mathrm{Find}\:\mathrm{the}\:\mathrm{cubic}\:\mathrm{equation}\:\mathrm{whose}\:\mathrm{roots} \\ $$$$\mathrm{are}\:\mathrm{the}\:\mathrm{radius}\:\mathrm{of}\:\mathrm{three}\:\mathrm{escribed}\:\mathrm{circles} \\ $$$$\mathrm{in}\:\mathrm{term}\:\mathrm{of}\:\mathrm{inradius},\:\mathrm{circumradius}\:\mathrm{and} \\ $$$$\mathrm{semiperimeter}. \\ $$ Answered by behi.8.3.4.1.7@gmail.com last updated on 05/Aug/17…
Question Number 18962 by Tinkutara last updated on 02/Aug/17 $$\mathrm{The}\:\mathrm{number}\:\mathrm{of}\:\mathrm{solutions}\:\mathrm{of}\:\mathrm{the}\:\mathrm{equation} \\ $$$$\mathrm{sin}^{\mathrm{5}} \:\theta\:+\:\frac{\mathrm{1}}{\mathrm{sin}\:\theta}\:=\:\frac{\mathrm{1}}{\mathrm{cos}\:\theta}\:+\:\mathrm{cos}^{\mathrm{5}} \:\theta\:\mathrm{where} \\ $$$$\theta\:\in\:\left(\mathrm{0},\:\frac{\pi}{\mathrm{2}}\right)\:,\:\mathrm{is} \\ $$ Answered by behi.8.3.4.1.7@gmail.com last updated on 02/Aug/17…
Question Number 84469 by jagoll last updated on 13/Mar/20 $$\mathrm{prove}\:\mathrm{that}\: \\ $$$$\mathrm{sin}\:\mathrm{3b}\:+\:\left(\mathrm{cos}\:\mathrm{b}+\mathrm{sin}\:\mathrm{b}\right)\left(\mathrm{1}−\mathrm{2sin}\:\mathrm{2b}\right) \\ $$$$=\:\mathrm{cos}\:\mathrm{3b} \\ $$ Answered by som(math1967) last updated on 13/Mar/20 $${sin}\mathrm{3}{b}+{cosb}−\mathrm{2}{sin}\mathrm{2}{bcosb}+\mathrm{sin}\:{b}−\mathrm{2sin}\:{b}\mathrm{sin}\:\mathrm{2}{b} \\…
Question Number 18893 by Tinkutara last updated on 01/Aug/17 $$\mathrm{Find}\:\mathrm{all}\:\mathrm{values}\:\mathrm{of}\:{x},\:{y}\:\mathrm{and}\:{k}\:\mathrm{for}\:\mathrm{which} \\ $$$$\mathrm{the}\:\mathrm{system}\:\mathrm{of}\:\mathrm{equations} \\ $$$$\mathrm{sin}\:{x}\:\mathrm{cos}\:\mathrm{2}{y}\:=\:{k}^{\mathrm{4}} \:−\:\mathrm{2}{k}^{\mathrm{2}} \:+\:\mathrm{2} \\ $$$$\mathrm{cos}\:{x}\:\mathrm{sin}\:\mathrm{2}{y}\:=\:{k}\:+\:\mathrm{1} \\ $$$$\mathrm{has}\:\mathrm{a}\:\mathrm{solution}. \\ $$ Answered by 433…
Question Number 18891 by Tinkutara last updated on 01/Aug/17 $$\mathrm{If}\:\mathrm{angles}\:{A}\:\mathrm{and}\:{B}\:\mathrm{satisfy}\:\sqrt{\mathrm{2}}\:\mathrm{cos}\:{A}\:= \\ $$$$\mathrm{cos}\:{B}\:+\:\mathrm{cos}^{\mathrm{3}} \:{B}\:\mathrm{and}\:\sqrt{\mathrm{2}}\:\mathrm{sin}\:{A}\:=\:\mathrm{sin}\:{B}\:− \\ $$$$\mathrm{sin}^{\mathrm{3}} \:{B},\:\mathrm{then}\:\mathrm{the}\:\mathrm{value}\:\mathrm{of}\:\mathrm{1620sin}^{\mathrm{2}} \left({A}\:−\:{B}\right) \\ $$$$\mathrm{is} \\ $$ Answered by behi.8.3.4.1.7@gmail.com last…
Question Number 18892 by Tinkutara last updated on 01/Aug/17 $$\mathrm{If}\:\mathrm{the}\:\mathrm{equation}\:\mathrm{sin6}{x}\:+\:\mathrm{cos4}{x}\:=\:−\mathrm{2}\:\mathrm{have} \\ $$$$\mathrm{a}\:\mathrm{family}\:\mathrm{of}\:\mathrm{nonnegative}\:\mathrm{solutions}\:{x}_{{k}} '\mathrm{s}, \\ $$$$\mathrm{where}\:\mathrm{0}\:\leqslant\:{x}_{\mathrm{1}} \:<\:{x}_{\mathrm{2}} \:<\:{x}_{\mathrm{3}} \:<\:….\:<\:{x}_{{k}} \:<\:{x}_{{k}+\mathrm{1}} \\ $$$$…..,\:\mathrm{then}\:\mathrm{the}\:\mathrm{value}\:\mathrm{of}\:\frac{\mathrm{1}}{\pi}\underset{{k}=\mathrm{1}} {\overset{\mathrm{1000}} {\sum}}\mid{x}_{{k}+\mathrm{1}} \:−\:{x}_{{k}} \mid\:\mathrm{is}…
Question Number 18847 by Tinkutara last updated on 30/Jul/17 $$\mathrm{In}\:\mathrm{an}\:\mathrm{equilateral}\:\mathrm{triangle}\:\mathrm{with}\:\mathrm{usual} \\ $$$$\mathrm{notations}\:\mathrm{the}\:\mathrm{value}\:\mathrm{of}\:\frac{\mathrm{27}{r}^{\mathrm{2}} {R}}{{r}_{\mathrm{1}} {r}_{\mathrm{2}} {r}_{\mathrm{3}} }\:\mathrm{is}\:\mathrm{equal}\:\mathrm{to} \\ $$ Answered by behi.8.3.4.1.7@gmail.com last updated on 31/Jul/17…
Question Number 18841 by mondodotto@gmail.com last updated on 30/Jul/17 Answered by Tinkutara last updated on 31/Jul/17 $$\sqrt{\mathrm{2}\:+\:\sqrt{\mathrm{2}\:+\:\sqrt{\mathrm{2}\left(\mathrm{1}\:+\:\mathrm{cos}\:\mathrm{8}\theta\right)}}} \\ $$$$=\:\sqrt{\mathrm{2}\:+\:\sqrt{\mathrm{2}\left(\mathrm{1}\:+\:\mathrm{cos}\:\mathrm{4}\theta\right)}}\:=\:\sqrt{\mathrm{2}\left(\mathrm{1}\:+\:\mathrm{cos}\:\mathrm{2}\theta\right)} \\ $$$$=\:\mathrm{2}\:\mathrm{cos}\:\theta \\ $$ Terms of…
Question Number 18830 by Joel577 last updated on 30/Jul/17 $$\mathrm{If}\:\mathrm{sin}\:\mathrm{2}{x}\:=\:{a} \\ $$$$\mathrm{find}\:\mathrm{the}\:\mathrm{simplest}\:\mathrm{expression}\:\mathrm{for}\:\mathrm{cos}\:{x} \\ $$ Commented by mrW1 last updated on 30/Jul/17 $$\mathrm{cos}\:\mathrm{2x}=\pm\sqrt{\mathrm{1}−\mathrm{a}^{\mathrm{2}} } \\ $$$$\mathrm{2cos}^{\mathrm{2}}…