In △ ABC, B & # 178; = AC, B = 60 °, then a
60°
From the cosine theorem, we know that B & # 178; = A & # 178; + C & # 178; - 2cos (b) * AC = A & # 178; + C & # 178; - AC
∵b²=ac
{ A & { 178; + C & { 178; - 2Ac = 0 deduces a = C
And ∵ B = 60 °
A triangle is an equilateral triangle
So a = 60 degrees
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