10. In polygon ABCDE, how many possible diagonals can be formed from one vertex A. 5 B. 4 C. 3 D. 2 11. What is the term that refers to a closed plane figure determined by the union of non-collinear A. angle C. line B. plane D. polygon 12. A polygon where all angles and sides are congruent is A. consecutive C. equiangular B. equilateral D. regular