Question Number 28648 by tawa tawa last updated on 28/Jan/18
$$\mathrm{If}\:\:\theta\:\:=\:\:\mathrm{log}_{\mathrm{e}} \left[\mathrm{tanh}\left(\frac{\mathrm{3}\pi}{\mathrm{8}}\right)\right]\:,\:\:\:\mathrm{Prove}\:\mathrm{that}\:\:\:\:\:\:\:\mathrm{3tanh}\left(\mathrm{2}\theta\right)\:=\:\mathrm{2}\sqrt{\mathrm{2}} \\ $$