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Question Number 10873 by Saham last updated on 28/Feb/17
without using calculator or table, find the exact value of  :  sin[tan^(−1) ((1/2))]
$$\mathrm{without}\:\mathrm{using}\:\mathrm{calculator}\:\mathrm{or}\:\mathrm{table},\:\mathrm{find}\:\mathrm{the}\:\mathrm{exact}\:\mathrm{value}\:\mathrm{of}\:\:: \\ $$$$\mathrm{sin}\left[\mathrm{tan}^{−\mathrm{1}} \left(\frac{\mathrm{1}}{\mathrm{2}}\right)\right] \\ $$
Answered by fariraihmudzengerere75@gmail.c last updated on 28/Feb/17
Answer   . sin [tan^(−1) (x)]=x/(√((1+x(2/))))   sin [tan^(−1) (1/2)]=((1/2)/( (√(1+(1/2)(2/)))))                                              =((1/2)/( (√(1+1/4))))                                   =((1/2)/( (√(5/4))))                                   =(1/2)/(√(5/4))                                    =(1/2)×((√4)/( (√5)))                                     =(1/( (√5)))                                     =((√5)/5)
$${Answer}\:\:\:.\:\mathrm{sin}\:\left[\mathrm{tan}^{−\mathrm{1}} \left({x}\right)\right]={x}/\sqrt{\left(\mathrm{1}+\boldsymbol{\mathrm{x}}\frac{\mathrm{2}}{}\right)} \\ $$$$\:\mathrm{sin}\:\left[\mathrm{tan}^{−\mathrm{1}} \left(\mathrm{1}/\mathrm{2}\right)\right]=\frac{\mathrm{1}/\mathrm{2}}{\:\sqrt{\mathrm{1}+\left(\mathrm{1}/\mathrm{2}\right)\frac{\mathrm{2}}{}}}\:\:\:\:\:\:\:\:\:\: \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\frac{\mathrm{1}/\mathrm{2}}{\:\sqrt{\mathrm{1}+\mathrm{1}/\mathrm{4}}} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\frac{\mathrm{1}/\mathrm{2}}{\:\sqrt{\mathrm{5}/\mathrm{4}}} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\left(\mathrm{1}/\mathrm{2}\right)/\sqrt{\mathrm{5}/\mathrm{4}} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\left(\mathrm{1}/\mathrm{2}\right)×\frac{\sqrt{\mathrm{4}}}{\:\sqrt{\mathrm{5}}} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\frac{\mathrm{1}}{\:\sqrt{\mathrm{5}}} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\frac{\sqrt{\mathrm{5}}}{\mathrm{5}} \\ $$$$ \\ $$$$ \\ $$$$\:\:\:\:\: \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\: \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\: \\ $$$$ \\ $$
Commented by Saham last updated on 28/Feb/17
God bless you sir.
$$\mathrm{God}\:\mathrm{bless}\:\mathrm{you}\:\mathrm{sir}. \\ $$

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