Question Number 143897 by liberty last updated on 19/Jun/21
Answered by bobhans last updated on 19/Jun/21
$$\:\:\mathrm{sin}\:^{\mathrm{2}} \:\frac{\pi}{\mathrm{8}}+\mathrm{cos}\:^{\mathrm{2}} \:\frac{\pi}{\mathrm{8}}+\mathrm{cos}\:^{\mathrm{2}} \:\frac{\mathrm{5}\pi}{\mathrm{8}}+\mathrm{sin}\:^{\mathrm{2}} \:\frac{\mathrm{5}\pi}{\mathrm{8}}=\mathrm{2} \\ $$