In the known isosceles triangle ABC, the angle a = 80 ° is used to find the degree of the other two angles step

If B = C, then 2B = 180-a = 180-80 = 100, B = C = 50
2. If a is the base angle, the other base angle is also 80 degrees, and the vertex angle is 180-80x2 = 20

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