Which transformation matrix would result in a 300 degrees counterclockwise rotation about the origin?

A counterclockwise rotation by θ uses the matrix [[cos θ, −sin θ], [sin θ, cos θ]]. For 300°, cos 300° = 1/2 and sin 300° = −√3/2, giving [[1/2, √3/2], [−√3/2, 1/2]]. This matches choice A.

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