In ∆ABC, if b2 + c2 − a2 = bc, then $\angle$A = ______.

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In ∆ABC, if b2 + c2 − a2 = bc, then $\angle$A = bbunderline(pi/3). Explanation: By cosine rule, `cos A = (b^2 + c^2 - a^2)/(2 bc) $\therefore$ cos A = (bc)/(2 bc) ...[b2 + c2 − a2 = bc] $\therefore$ cos A = $\frac{1}{2}$ $\therefore$ angle A = pi/3`

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