Предмет: Алгебра, автор: Burro

Вычеслить 5-6cos квадрат альфа, если sin альфа = -38

Ответы

Автор ответа: odes1

Вычисляем по основному тригонометрическому тождеству:sin^2x+cos^2x=1,
из него следует, что cos^2a=1-sin^2a
если sina=-3/8, то sin^2a=9/64,
cos^2a=1-9/64=64/64-9/64=55/64
подставляем cos^2a
5-6*(55/64)=5-5(5/32)=-5/32

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