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The ducks had been heading due South, at 8 (m/s), but were hit by the side wind from the West at 4.5 (m/s).
To counter this, they have to have a West-ward component of 4.5. But this means that, if their angle (west of south) is alpha,
8*sin(alpha) = 4.5
=> sin(alpha) = 4.5/8 = 0.5625
=> alpha = Arcsin(0.5625) = 34.23 degrees (WoS)