cos(40 π t) sin(60 π t)

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1 Answer

sin(A)+sin(B)≡2sin(½(A+B))cos(½(A-B)), therefore, if ½(A+B)=60πt and ½(A-B)=40πt:

A+B=120πt

A-B=80πt

2A=200πt, A=100πt, 2B=40πt, B=20πt. 

Therefore, sin(100πt)+sin(20πt)=2sin(60πt)cos(40πt), and:

cos(40πt)sin(60πt)=½(sin(100πt)+sin(20πt)).

by Top Rated User (1.2m points)

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