Chapter 10 - Radical Expressions and Equations - 10-1 The Pythagorean Theorem - Practice and Problem-Solving Exercises - Page 617: 12

b=1.333

The Pythagorean Theorem states that for a right triangle, $a^{2} +b^{2} = c^{2}$. Thus, we plug in the values given for a, b, or c, and then we use these values to find the missing value: $1^{2} + b^{2} = (5/3)^{2} \\\\ 1 + b^{2} =2.777... \\\\ b^{2} =1.777... \\\\ b=1.333$