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8sin20 sin40 sin80 |
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Answer» LHS = 8sin20° .sin40°.sin80° =4{ 2sin20.sin80°}sin40° =4{cos(60) - cos100°} sin40° =4×1/2sin40° - 4cos100°.sin40° =2sin40° - 2{2sin40°cos100°} =2sin40° -2{ sin140° -sin60° } =2sin40° -2sin40° + 2sin60° =√3 = RHS |
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