A surveyor starts at the center of a circular park with radius 7 miles.

He walks 3 miles directly east and drives a stake into the ground at point $\displaystyle A.$

He walk directly north until he reaches the perimeter of the park.

Then he walks directly west until he is directly north of the center,

. . and drives a stake into the ground at point $\displaystyle B.$

Find the distance $\displaystyle \overline{AB}.$

[The shortest solution, please.]

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