Ответы и объяснения

2012-09-30T22:09:34+00:00

(sin(π/8)+sin(3π/8))*(cos(3π/8)-cos(π/8))=

sinα+sinβ=2*sin(α+β)/2*cos(α-β)/2;

cosα-cosβ=(-2)*sin(α+β)/2*sin(α-β)/2;

 

(sin(π/8)+sin(3π/8))*(cos(3π/8)-cos(π/8))=(2sin(π/4)*cos(π/8))*(-2sin(π/4)*sin(π/8))=

-2cos(π/8)*sin(π/8)=-sin(π/4)=-√2/2.