Тригонометрия,помогите

Question

Тригонометрия,помогите

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Answer 1

Cosa-cosb=-2sin((a+b)/2)sin((a-b)/2)
Cos(19p/12)-cos(p/12)=-2sin(20p/24)sin(18p/24)=-2sin(5p/6)sin(3p/4)=-2sin(p-p/6)sin(p-p/4)=-2sin(p/6)sin(p/4)=-2*1/2*sqrt(2)/2=-sqrt(2)/2

Comments

Sqrt=корень