## Functions Modeling Change: A Preparation for Calculus, 5th Edition

$1.330$ rad.
First, divide both sides by $3$ to get $$\cos \theta = \frac{0.714}{3}$$ Since $\cos \theta = \frac{0.714}{3}$, the equation can be rearranged to say $\theta= \arccos(0.714/3)=1.330 \, \textrm{rad.}$ (Use a calculator to calculate the value.)