Solution: \( 225^\circ \) lies in the third quadrant, where sine is negative. Reference angle: \( 225^\circ - 180^\circ = 45^\circ \). Thus, \( \sin 225^\circ = -\sin 45^\circ = -\frac{\sqrt{2}}{2} \). \boxed{-\dfrac{\sqrt{2}}{2}}

Sun, 03 May 2026 19:40:07 +0000

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