3. The figure on the right is formed by stacking three right triangles, and $\overline { O D } = 8$.\\
Question: What is the height $\overline { A B }$ of right triangle $O A B$?\\
(1) 1\\
(2) $\sqrt { 6 } - \sqrt { 2 }$\\
(3) $\sqrt { 7 } - 1$\\
(4) $\sqrt { 3 }$\\
(5) 2\\
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