Which of the following are true statements about any regular polygon?
a. it is convex
b. it is concave
c. it is a quadrilateral
d. its sides are line segments
e. all of its sides are congruent
f. all of its angles are congruent

Answer
A. It is convex.
D. Its sides are line segments.
E. all of its sides are congruent.
F. All of its angles are congruent.

Explanation
In geometry, a regular polygon is a polygon whose all angles are equal and all sides are equal. That it is equiangular and equilateral respectively.
The statement that are true about a regular polygon from the choices given are:
A. It is convex. 
D. Its sides are line segments. 
E. all of its sides are congruent. 
F. All of its angles are congruent.