Category: Trigonometry

Question Number 68446 by 9102176137086 last updated on 10/Sep/19 $$\cos (x-60)+\cos (x-30)=\sin x$$$$prove$$ Commented by mr W last updated on 10/Sep/19 $$nottrue!$$$${for}\:{x}=\mathrm{30}°:…

Question Number 133950 by liberty last updated on 25/Feb/21 $$\mathrm{Find}\mathrm{the}\mathrm{value}\mathrm{of}$$$$\sin {}^2\left(\frac{9\pi }{10}\right).\sin {}^2\left(\frac{7\pi }{10}\right).$$ Answered by bobhans last updated on 25/Feb/21 Terms of…

Question Number 68397 by Faradtimmy last updated on 10/Sep/19 Answered by $@ty@m123lastupdatedon10/Sep/19$$\left(a\right)LHS=\sqrt{3}\cos \theta -\sin \theta$$$\$=2(\frac{\sqrt{3}}{2}\cos \theta -\frac{1}{2}\sin \theta )$$$$=2(\cos 30\cos \theta -\sin 30\sin \theta )$$$$=2\cos (30+\theta )$$$${Pl}.\:{check}\:{the}\:{question}.…

Question Number 133851 by physicstutes last updated on 24/Feb/21 $$\mathrm{A}\mathrm{circle}\mathrm{of}\mathrm{radius}r\mathrm{is}\mathrm{such}\mathrm{that}\mathrm{it}\mathrm{subtends}\mathrm{an}$$$$\mathrm{angle}\mathrm{of}\alpha \mathrm{at}\mathrm{its}\mathrm{centre}.\mathrm{A}\mathrm{chord}\mathrm{cuts}\mathrm{the}\mathrm{circle}\mathrm{such}$$$$\mathrm{that}\mathrm{it}\mathrm{divides}\mathrm{the}\mathrm{circle}\mathrm{into}\mathrm{two}\mathrm{segments}\mathrm{of}\mathrm{areas}\mathrm{in}$$$$\mathrm{the}\mathrm{ratio}1:5.\mathrm{show}\mathrm{that}$$$$\sin \alpha =\alpha -\frac{\pi }{3}$$ Terms of Service Privacy Policy…

Question Number 68078 by anaplak last updated on 04/Sep/19 Answered by Smail last updated on 04/Sep/19 $$C+iS=1+z(cos\theta +isin\theta )+\frac{z^2}{2!}(cos2\theta +isin2\theta )+\dots$$$$=\mathrm{1}+{ze}^{{i}\theta} +\frac{\left({ze}^{{i}\theta} \right)^{\mathrm{2}} }{\mathrm{2}!}+…={e}^{{ze}^{{i}\theta} } ={e}^{{zcos}\theta}…