# Chapter 11 - Surface Area and Volume - Get Ready! - Page 685: 2

8$\sqrt 2$

#### Work Step by Step

We use the Pythagorean Theorem: $a^{2}$+$b^{2}$=$c^{2}$ $a^{2}$+$4^{2}$=$12^{2}$ $a^{2}$+16=144 $a^{2}$=128 a=8$\sqrt 2$

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