Answer
$1.30$
Work Step by Step
Suppose $\theta = \cos^{-1} (\dfrac{\sqrt 7}{10})$
This gives: $\cos \theta=\dfrac{\sqrt 7}{10}$
Now, substitute the equation into a calculator (in radian mode).
Therefore, we have $ \cos^{-1} (\dfrac{\sqrt 7}{10})=1.30$
