Предмет: Математика, автор: Аноним

Помогите, пожалуйста! Срочно! 2sin50sin40
Объясните, пожалуйста, и по какой формуле

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Автор ответа: CTATUCT
0
Зная, что sin(90-a)=cosa приведем sin 50 в cos 40, тогда 2cos40sin40=Sin80 по формуле двойного угла или половины угла
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