Math, asked by sameenzeenath47, 1 year ago

Sin10 sin50 sin70 =1/8

Answers

Answered by subhikshamrth
1

Sin10sin50sin70

= 1/2(2sin10sin50sin70)

And 2sinAsinB = cos (A-B) - cos (A+B)

So 1/2(2sin10sin50sin70) = 1/2(sin10{cos20 - cos120})

And cos 120 = cos (90 + 30) = 1/2

So 1/2 {sin10(cos20 +1/2)}

= 1/2sin10cos20 +1/4sin10

= 1/4(2sin10cos20) + 1/4sin10

As 2sinAcosB = sin(A+B)-sin(A-B)

= 1/4 (sin 30 -sin10) +1/4sin10

= 1/4sin30

= 1/8 = RHS

Hope this helps u dude

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