Answer
$(1, \sqrt 3,7) \Longrightarrow (2, \frac{\pi}{3},7) $.
Work Step by Step
We have $$ x=1, \quad y =\sqrt 3, \quad z=7.$$
Now, we have
$$ r=\sqrt{x^2+y^2}=\sqrt{4}=2,$$
$$\theta =\tan^{-1}y/x=\tan^{-1}\frac{1}{\sqrt{3}}=\frac{\pi}{3}=\frac{\pi}{3},$$
$$ z=7.$$
So, $(1, \sqrt 3,7) \Longrightarrow (2, \frac{\pi}{3},7) $.
