Question Number 140500 by qaz last updated on 08/May/21
$$\mathrm{tan}\:^{\mathrm{2}} \mathrm{1}°+\mathrm{tan}\:^{\mathrm{2}} \mathrm{2}°+\mathrm{tan}\:^{\mathrm{2}} \mathrm{3}°+…+\mathrm{tan}\:^{\mathrm{2}} \mathrm{89}°=\frac{\mathrm{15931}}{\mathrm{3}}\:\:\:\:\:??? \\ $$