Question Number 171858 by Mikenice last updated on 21/Jun/22
$${solve}: \\ $$$${find}\:{the}\:{value}\:{of}\:{x}\:{and}\:{y}\:{between}\:\mathrm{0}^{°\:} {and}\mathrm{180}^{°} \:{which}\:{satisfy}\:{the}\:{simultaneous}\:{eqn} \\ $$$${sin}\left({x}+{y}\right)=\frac{\sqrt{\mathrm{2}}}{\mathrm{2}} \\ $$$${cos}\mathrm{2}{x}=−\frac{\mathrm{1}}{\mathrm{2}} \\ $$