In a triangle ABC AB = BC. Angle B is 80. Find the outer corner BCD.
| September 9, 2021 | education
Since, according to the condition, AB = BC, the triangle ABC is isosceles, and therefore the angles at the base of the AC are equal to each other.
The sum of the angles of the triangle is 180, then the angle BAC = ACB = (180 – 80) / 2 = 100/2 = 50.
The angle АСD is expanded, its value is 180, then the external angle ВСD = 180 – АСВ = 180 – 50 = 130.
Answer: External angle ВСD = 130.
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