Answer
$c = 104$ inches
Work Step by Step
$c^{2} = a^{2} + b^{2} - 2abcos(\theta)$
$c^{2} = (120)^{2} + (66)^{2} - 2(120)(66)cos(60)$
$c^{2} = 14400 + 4356 - 15840cos(60)$
by GDC / calculator
$c^{2} = 18756 - 7920$
$c^{2} = 10836$
$c = \sqrt {10836}$
$c = 104.0961...$ inches
$c = 104$ inches