Доказать, что:
[tex] \sin(10) \times \sin(50) \times \sin(70) = \frac{1}{8} [/tex]

sin10*sin50*sin70*cos10/cos10=sin20*sin50*sin(90-20)/(2cos10)==sin20sin50cos20/(2cos10)=sin40*sin50/(4cos10)=sin40*sin(90-40)/(4cos10)==sin40cos40/(4cos10)=sin80/(8cos10)=sin(90-10)/(8cos10)=cos10/(8cos10)==1/8

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