Jawabanmu

2014-02-16T20:13:17+07:00
1/2(sin(75+15)+sin(75-15))

1/2(sin 90 + sin 60)

1/2(1+(sqrt3)/2)

answer:( 2+sqrt3)/ 4
Cos(20) Cos(40) Cos(80)
= [1/sin(20)](1/2)[2sin(20)Cos(20) Cos(40) Cos(80)]
= [1/sin(20)](1/4)[2sin(40)Cos(40) Cos(80)]
= [1/sin(20)](1/8)[2sin(80)Cos(80)]
= [1/sin(20)](1/8)sin(160)
= 1/8, since sin(160) = sin(20)
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