Question

add the sum of (m²-mn+n) and (mn-n+2) to the product of (m+n-3) and (m-n+1)​

Answer 1

∵ ∆ABC is an equilateral triangle

∴ A = 60°

∵ ABEC is a cyclic quadrilateral

∴ ∠A + ∠E = 180° (Sum of opposite angles)

⇒ 60° + ∠E = 180°

⇒ ∠E = 180° – 60° = 120°

∴ m ∠BEC = 120