Category: Trigonometry

Question Number 126562 by mey3nipaba last updated on 21/Dec/20 $$Provethat2\sin \frac{\theta +\varphi }{2}\cos \frac{\theta -\varphi }{2}=\sin \theta +\sin \mathrm{\varnothing }$$$$Ineedhelpimmediatelyplease$$ Commented by mr W last updated on 21/Dec/20 $$\theta =\frac{\theta +\phi }{2}+\frac{\theta -\phi }{2}$$$$\varphi=\frac{\theta+\varphi}{\mathrm{2}}−\frac{\theta−\varphi}{\mathrm{2}}…

Question Number 126499 by liberty last updated on 21/Dec/20 $$4\arctan \left(\frac{1}{5}\right)-\arctan \left(\frac{1}{239}\right)=?$$ Answered by benjo_mathlover last updated on 21/Dec/20 $$letx={\tan }^{-1}\left(\frac{1}{5}\right)\Rightarrow \tan x=\frac{1}{5}$$$$\:\mathrm{tan}\:\mathrm{2}{x}=\frac{\mathrm{2tan}\:{x}}{\mathrm{1}−\mathrm{tan}\:^{\mathrm{2}} {x}}\:=\:\frac{\mathrm{2}/\mathrm{5}}{\mathrm{1}−\mathrm{1}/\mathrm{25}}\: \…

Question Number 126381 by liberty last updated on 20/Dec/20 $$\arctan 1+\arctan 2+\arctan 3=?$$ Answered by benjo_mathlover last updated on 20/Dec/20 $$(\bullet )\arctan 1+\arctan 2=\arctan \left(\frac{1+2}{1-1.2}\right)$$$$\arctan (-3)$$$$\left(\bullet\bullet\right)\:\mathrm{arctan}\:\left(−\mathrm{3}\right)+\mathrm{arctan}\:\left(\mathrm{3}\right)=\mathrm{arctan}\:\left(\frac{−\mathrm{3}+\mathrm{3}}{\mathrm{1}−\left(−\mathrm{3}\right)\left(\mathrm{3}\right)}\right) \…

Question Number 60814 by Forkum Michael Choungong last updated on 26/May/19 $$findxgiventhat$$$$9^{{sin}^{2}x}+9^{{cos}^{2}x}=2$$$$$$ Answered by $@ty@m…

Question Number 126148 by Study last updated on 17/Dec/20 $$A,B,CandDareanglesoftetragon$$$$ifA+D={240}^{°},C+D=200g$$$$B+D=\frac{2\pi }{3},findD=???$$ Answered by mahdipoor last updated on 17/Dec/20 $${A}+{B}+{C}+{D}=\mathrm{360}^{°}…