The value of sin 20^o.sin40^o,sin60^o.sin80^o=

• 1/16
• 3/16
• 1/8
• 1/4

sin60 = /2

sin20sin40sin80
= sin20 sin(60-20)sin(60+20) = ¼ sin3(20) i.e ¼ sin60
(identity sin sin (60 + ) sin(60 -) = ¼ sin 3)

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