The bisectors of angles A and B of an equilateral triangle ABC meet at point O. Find the angle AOB.

Since the triangle is equilateral, all of its angles are 60. Angle BAC = BCA = ABC = 60.

AA1 is the bisector of the angle BAC, then the angle OAB = 60/2 = 30.

BB1 is the bisector of the angle ABC, then the angle ABO = 60/2 = 30.

Then the angle AOB = 180 – OAB – ABO = 180 – 30 – 30 = 120.

Answer: Angle AOB is 120.



One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.