Предмет: Алгебра, автор: wwwdanil1998

Найти -49cos2a, если cos a =0,2

Ответы

Автор ответа: erzhan9210

cos2a=2cos²a-1
-49cos2a = -49(cos²a-1) = -49(0,2²-1) = -49(0,04-1) = -49*(-0,96) = 47,04

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