In △ ABC, if (A2 + c2-b2) tanb = 3aC, then the value of angle B is______ .
∵ in △ ABC, the opposite sides of angles a, B and C are a, B and C respectively, (A2 + c2-b2) tanb = 3aC, ∵ 2Ac · CoSb · tanb = 3aC, ∵ SINB = 32, B = π 3 & nbsp; or & nbsp; b = 2 π 3, so the answer is: π 3 & nbsp; or 2 π 3
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