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Doctors Medicines MCQs Q&A

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1 Answers

$sin(A+-B)=sinAcosB+-cosAsinB$

Therefore

$sin(alpha+beta)=sinalphacosbeta+cosalphasinbeta$

$sin(alpha-beta)=sinalphacosbeta-cosalphasinbeta$

$sin(alpha+beta)-sin(alpha-beta)=(sinalphacosbeta+cosalphasinbeta)-(sinalphacosbeta-cosalphasinbeta)$

$=cancel(sinalphacosbeta)+cosalphasinbeta-cancel(sinalphacosbeta)+cosalphasinbeta$

$=2cosalphasinbeta$

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