Answer
$113.50097^{\circ}$
Work Step by Step
$y=$arccos $-0.39876459=\cos^{-1} -0.39876459$
Ensuring that the calculator is in degrees, we type $\cos^{-1} -0.39876459$ into the calculator and solve:
$\cos^{-1} -0.39876459\approx113.50097^{\circ}$
Therefore, $y=$arccos $-0.39876459\approx113.50097^{\circ}$.
