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Grade 12Trigonometry

1)show that sin 20.sin40.sin60.sin80 = 3/16
here all angles are in degress
2)prove that tanA+secA-1/tanA-secA+1 = 1+sinA/cosA

Profile image of Raghav Rao
9 Years agoGrade 12
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1 Answer

Profile image of Vikas TU
9 Years ago
Put the value of sin60 in the L.H.S and then,
apply formulae: 2sinAcosB in sequence one by onne.
 
Take sin20 common and apply for 2sin40sin80 and so on.

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