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Mathematics, 20.03.2020 22:05 sarahelisabeth444

Which of the following are identities? Check all that apply.
A. cos(x + y) + cos(x - y) = 2cosxcosy
B. sin(x + y)- sin(x - y) = 2cosxsiny
C. sin(x - pi)= - sinx
D. cos(x + y) + cos(x - y) = cos^2x-sin^2y

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Which of the following are identities? Check all that apply.
A. cos(x + y) + cos(x - y) = 2cos...
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