  The present paper aims to solve some problems proposed by Lassak about the
reduced spherical polygons. The main result is to show that the regular
spherical n-gon has the minimal perimeter among all reduced spherical polygons
of fixed thickness less than {\pi}/2 and with at most n vertices. In addition,
we determine the maximal diameter of every reduced spherical polygons with a
fixed thickness less than {\pi}/2. We also find the smallest spherical radius
that contains every reduced spherical polygons with a fixed thickness less than
{\pi}/2.
