In triangle ABC, where AD = BD = CD, we have an equilateral triangle. In an equilateral triangle, all sides are equal, and all angles are also equal. Therefore, each angle of the triangle, including angle BAC, is 60 degrees. Thus, the size of angle BAC is 60 degrees in this case.
In triangle ABC, the given condition that AD = BD = CD indicates an equilateral triangle, where all sides are equal. In an equilateral triangle, each interior angle is also equal. Therefore, angle BAC, being one of the interior angles of triangle ABC, is 60 degrees.
This is because an equilateral triangle has three equal angles, and the sum of all interior angles in a triangle is always 180 degrees. In this case, each angle in triangle ABC is 60 degrees, as 3 times 60 equals 180.
The equilateral nature of the triangle ensures that angle BAC, along with angles BCA and CAB, is precisely 60 degrees. Thus, the size of angle BAC in triangle ABC is unequivocally determined to be 60 degrees based on the given conditions.
Complete question:
In the triangle ABC, AD = BD = CD. What is the size of angle BAC?