If it is a regular polygon is then it is equilateral

This might be a t or f. if this would be true,

regular polygons all contain an equal length in each side, polygons in general sometimes don't have equal sides. however, another kind of polygons are regular ones. those are polygons that use specific number of sides with the length of each one being the same

if it is false, polygons in general dont have equal sides.

That's true. If it is a regular polygon, then all of its sides have the same length.