Question

In a ∆ABC, if c² + a² – b² = ac, then ∠B =

• A. $\frac{\pi}{6}$
• B. $\frac{\pi}{4}$
• C. $\frac{\pi}{3}$
• D. None of these

Answer 1

Answer: (C)

$\frac{\pi}{3}$

Answer 2

c² + a² – b² = ac ⇒ = $\frac { 1 } { 2 }$

⇒ cos B = $\frac { 1 } { 2 }$ ⇒ ∠B = 60⁰