Question Number 83513 by jagoll last updated on 03/Mar/20
$$\mathrm{If}\:\mathrm{m}\:\mathrm{tan}\:\left(\theta−\mathrm{30}^{\mathrm{o}} \right)\:=\:\mathrm{n}\:\mathrm{tan}\:\left(\theta+\mathrm{12}^{\mathrm{o}} \right) \\ $$$$\mathrm{prove}\:\mathrm{that}\:\mathrm{cos}\:\mathrm{2}\theta\:=\:\frac{\mathrm{m}+\mathrm{n}}{\mathrm{2}\left(\mathrm{m}−\mathrm{n}\right)} \\ $$
Commented by mind is power last updated on 04/Mar/20
$${false}\:\theta=−\mathrm{12}\Rightarrow{m}=\mathrm{0} \\ $$$$\Rightarrow{cos}\left(−\mathrm{24}\right)=−\frac{\mathrm{1}}{\mathrm{2}}\:\:{false} \\ $$$$ \\ $$
Commented by jagoll last updated on 04/Mar/20
$$\mathrm{oo}\:\mathrm{this}\:\mathrm{question}\:\mathrm{wrong}.\:\mathrm{thank}\:\mathrm{you} \\ $$$$\mathrm{sir} \\ $$