Question

sin10°乘sin30°乘sin50°乘sin70°

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Answer 1

sin10°乘sin30°乘sin50°乘sin70°
=cos20°乘cos40°乘cos60°乘cos80°
=1/2cos20°乘cos40°乘cos80°
=1/2cos20°乘sin20°乘cos40°乘cos80°除sin20°
=1/4sin40°乘cos40°乘cos80°除sin20°
=1/8sin80°乘cos80°除sin20°
=1/16sin160°除sin20°=1/16

Answer 2

sin10*sin50*sin70
=cos20cos40cos80
=sin20cos20cos40cos80/sin20
=1/2 sin40cos40cos80/sin20
=1/4 sin80cos80/sin20
=1/8 sin160/sin20
=1/8 sin20/sin20
=1/8

sin10°sin30°sin50°sin70°
=sin30*1/8
=1/8*1/2
=1/16

Answer 3

0.0625