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Ray AC and ray BA are not opposite rays because they do not share the same endpoint. Ray AC starts at A, while ray BA starts at B.

Conditions: The rays are named $\overrightarrow{AC}$ and $\overrightarrow{BA}$.; Points A, B, and C are on a line.

Ray AC and ray BA are not opposite rays because they do not share the same endpoint. Ray AC starts at A, while ray BA starts at B.

Conditions: The rays are named $\overrightarrow{AC}$ and $\overrightarrow{BA}$.; Points A, B, and C are on a line.