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Deepak

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· 1 Months ago

cos^2a - cos^2b = cos(a+b).cos(a-b)

Question:
cos (A+B). cos (A-B) is given by :
Options:
A) cos2 A-cos2B
B) cos (A2 - B2)
C) cos2 A - sin2B
D) sin2 A - cos2B
Solution:
Ans: (c)

cos (A+B). cos (A-B) = cos2 A- sin2 B

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