Cos120° = Cos(90° + 30°) = - Sin30° = - 0,5
Sin240° = Sin(180° + 60°) = - Sin60° = - √3/2
Второй способ:
Cos120° = Cos(180° - 60°) = - Cos60° = - 0,5
Sin240° = Sin(270° - 30°) = - Cos30° = - √3/2
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Verified answer
Cos120° = Cos(90° + 30°) = - Sin30° = - 0,5
Sin240° = Sin(180° + 60°) = - Sin60° = - √3/2
Второй способ:
Cos120° = Cos(180° - 60°) = - Cos60° = - 0,5
Sin240° = Sin(270° - 30°) = - Cos30° = - √3/2