Question Number 151082 by mathdanisur last updated on 18/Aug/21
Commented by Mokmokhi last updated on 18/Aug/21
$$\mathrm{This}\:\mathrm{can}\:\mathrm{be}\:\mathrm{proven}\:\mathrm{starting}\:\mathrm{from}\:\mathrm{left}. \\ $$$$\mathrm{By}\:\mathrm{substituting}\:{u}=\frac{\pi}{\mathrm{2}}−{x}. \\ $$$$\mathrm{After}\:\mathrm{evaluation}.\:\mathrm{By}\:\mathrm{dummy}\:\mathrm{variables}\:\mathrm{done}. \\ $$