Answer
$125.487°$
Work Step by Step
Use the property of Direction Cosines given here:
$\cos^2 α + \cos^2 β + \cos^2 γ = 1$
Given that $α = 60°$, $β = 50°$ and γ is obtuse
$\cos^2 (60°) + \cos^2 (50°) + \cos^2 γ = 1$
$(0.5)^2 + 0.413 + \cos^2 γ = 1$
$0.663 + \cos^2 γ = 1$
$\cos^2 γ = 0.337$
$\cos γ= 0.58$
$γ = 54.513°$
$180 - 54.513 = 125.487°$
