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Prove the identity cos(x-y)-cos(x+y)=2sinxsiny

User FarshidABZ
by
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1 Answer

7 votes

Answer:

see the procedure

Explanation:

we know that


cos(X - Y) = cosX cosY + sinX sinY\\cos(X + Y) = cosX cosY - sinX sinY

so


cos(X - Y)-cos(X + Y)=cosX cosY + sinX sinY-(cosX cosY - sinX sinY)


cos(X - Y)-cos(X + Y)=cosX cosY + sinX sinY-cosX cosY + sinX sinY


cos(X - Y)-cos(X + Y)=sinX sinY+ sinX sinY


cos(X - Y)-cos(X + Y)=2sinX sinY ----> is verified

User Svarr
by
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