Question

Помогите решить подробно

Answer 1

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Answer 2

$2cos( frac{ pi }{2}- alpha )= sqrt{2} \ cos( frac{ pi }{2}- alpha )=sin alpha \ 2sin alpha =sqrt{2} \ sin alpha = frac{ sqrt{2} }{2} \ alpha = frac{ pi }{4} +2 pi n$
n∈Z