In triangle ABC, AB=AC and D is a point on line AC so that line BD bisects angle ABC. If AD=DC, what is the measure, in degrees, of angle A?
If BD both bisects AC and angle(B), then triangle(ABC) is an isosceles triangle with AB = BC.
Since AB = AC, AB = AC = BC, making the triangle equilateral.
Therefore, angle(A) = 60o.