sin2A−sin2B +sin2C=? [ যখন, A+B+C=π]
A. 2cosA sinB cosC
B. 4 cosA sinB cosC
C. cosA sinB cosC
D. cosA tanB cosC
সঠিক উত্তরঃ
B.
4 cosA sinB cosC
Explanation: 
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