# In triangle ABC, sides AC and BC are equal, angle C is 98. Find the outer angle at vertex B.

July 29, 2021 | education

| Triangle ABC is isosceles, in an isosceles triangle the angles at the base are equal. Angle C is the angle at the apex, so the angles at the base are equal:

angle A = angle B = (180 ° – 98 °): 2 = 82 °: 2 = 41 °.

Outside apex angle B = 180 ° – 41 ° = 139 °.

Answer: The outside angle at the vertex B is 139 °.

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.