The vector $\overrightarrow{P Q}$ is given by $Q - P = (2,7) - (1,-4) = (1,11)$.
The vector $\overrightarrow{P R}$ is given by $R - P = (-2,2) - (1,-4) = (-3,6)$.
The vector $\overrightarrow{Q R}$ is given by $R - Q = (-2,2) - (2,7) = (-4,-5)$.
The vector
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