  In this paper are given some estimates of precision of the Huygens
approximation $x \approx \frac{2}{3} \sin x + \frac{1}{3} \tan x,$ for right
neighbourhood of zero, by determining some boundaries for the Huygens function
$f(x) = \frac{2}{3} \sin x + \frac{1}{3} \tan x,$ for $x \in \left(0,
\frac{\pi}{2} \right)$, in forms of some polynomial and some rational
functions.
