Which one of the following equations is correct 1 Cos 45' decrease plus sin 45' decrease equals 1?

The correct equation is (\cos(45^\circ) + \sin(45^\circ) = 1) when considering their values. Both (\cos(45^\circ)) and (\sin(45^\circ)) equal (\frac{\sqrt{2}}{2}), so their sum is (\sqrt{2}), not 1. Therefore, the equation as stated is incorrect.