Answer
Unknown length of the triangle $\approx 14.0$ cm
Work Step by Step
Let $x =$ unknown length of the triangle
$a^{2} + b^{2} = c^{2}$
$17^{2} + x^{2} = 22^{2}$
$289 + x^{2} = 484$
$x^{2} = 195$
$x = \sqrt 195$
$x = 13.964...$
$x \approx 14.0$ cm