Question Detail

(\cos(-225^\circ) = \cos(225^\circ)) because cosine is even. (225^\circ = 180^\circ + 45^\circ), so (\cos(225^\circ) = -\cos(45^\circ) = -\frac{\sqrt{2}}{2}). Wait, that gives negative. Let's recalc: (\cos(-225^\circ) = \cos(225^\circ) = \cos(180^\circ+45^\circ) = -\cos45^\circ = -\frac{\sqrt{2}}{2}). That is not among the options. However, (\sin(-225^\circ) = \frac{\sqrt{2}}{2}). Possibly the question meant (\sin(-225^\circ)). Given the options, (\frac{\sqrt{2}}{2}) is the answer for sine. Assuming a misprint, A is the likely intended answer.