Amy notes that arcs ADB and AEB are semicircles and that ABDC is equilateral. Because ZBCD is a central angle, she can say that m BD = 60°. She uses these facts to determine MAD = IDE = MAE = 120°. Finally, she concludes AADE is equilateral because congruent arcs are
intercepted by congruent chords.
Why is ABDC is equilateral?
A Triangle BDC is equilateral because diameter AB is a perpendicular bisector of chord BD.
Св. Triangle BDC is equilateral because arcs BD and BE are two arcs with the same radius and center,
Triangle BDC is equilateral because the sum of the three angle measures in AADE is the same as the measure of a semicircle.
Triangle BDC is equilateral because the distance between all three vertices is equal to the radius of the circle.
DD