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Grade 12th passTrigonometry

Sin 7theta/ sintheta in terms of cos theta give the answer

Profile image of Amisha
7 Years agoGrade 12th pass
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1 Answer

Profile image of Vikas TU
7 Years ago
Hiii Amisha
Sin 7Q / SinQ
expand 7Qas (6Q + Q)
and apply the formula sin(A+B)
so it wil be sin (6Q+Q)/ Sin Q
=> (Sin6Q * CosQ )/SinQ + Cos 6Q 
now exapnd Sin6Q as (5Q + Q)
and keep on calculting, 
The ans will come as CosQ+Cos2Q+Cos3Q+Cos4Q+Cos5Q+Cos6Q