2. A puck m₁ is sliding without friction on ice at 5 m/s along +x direction. It collides with another puck m₂ initially at rest. After collision, m₁ no longer moves along +x and its speed reduces to 4 m/s. Given m₂ = 3m₁, find θ₁ + θ₂ =
(A) 75°
(B) 90°
(C) 115.66°
(D) 121.33°
(E) 135°

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