Answer
$b = 2\sqrt21$ yards
Work Step by Step
Plugging in given values into the Pythagorean Theorem gives:
$4^2 +b^2 = 10^2$
Simplify by subtracting $4^2$ from both sides:
$b^2 = 10^2-4^2 = 100-16 = 84$
To Simplify $b^2 = 84$, take the square root of both sides:
$\sqrt b^2 = \sqrt 84 = \sqrt {4 \times 21}$
Finally, simplifying the radical gives the answer:
$b = 2\sqrt21$ yards
