Answers

2016-04-06T16:54:28+05:30
sin20   sin40 sin60 sin80
= 3/2 . sin 20 .sin (60 - 20) sin (60+20)
= 3/2 . sin 20.(sin 2 60 - sin 2 20)
= 3/2 .sin 20 . (3/4 - sin 2 20)
 = 3/8 .(3 sin 20 - 4 sin 3 20)
= 3/8 .(sin 3 . 20)
= 3/8 sin 60
= 3/16
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2016-04-06T17:31:12+05:30
sin20. sin 40. sin60. sin80

=> sin60[sin20.sin40.sin80]

=>√3/2[sin20.sin(60-20).sin(60+20)]

=>√3/2[sin 3(20)/4]

=>√3/2[sin 60/4]

=>√3/2[√3/2*4]

=>√3/2*√3/8

=3/16
 
hope it's help u
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