To find $\overrightarrow{P_1P_2}$, subtract the coordinates of $P_1$ from $P_2$:
\[
\overrightarrow{P_1P_2} = P_2 - P_1 = (2, 1, -1) - (-2, 0, 2) = (2 + 2, 1 - 0, -1 - 2) = (4, 1, -3).
\]
Similarly, to find $\overrightarrow{P_1P_3}$, subtract the coordinates of
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