sin10*sin50*sin70=1/8?
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Since sin(n) = cos(90-n), this is equivalent to cos(20) * cos(40) * cos(80). Now:
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.
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.
Anonymous:
HEYA, could you explain more??
what you want to know
after converting in cos, what u did??
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