Question

Which are identities (check all that apply) :

cos^2 3x - sin^2 3x = cos6x

(sinx + cosx)^2 = 1 + sin2x

sin^6 x + cos^6 x = 4 - 3sin^2 2x

sinx + sin5x = tan3x

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Which of the following are identities (check all that apply :

cos(x + y) + cos(x - y) = cos^2 x - sin^2 y

sin(x + y) - sin(x - y) = 2cosx siny

cos(x + y) + cos(x - y) = 2cosx cosy

sin(x - pi) = - sinx

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for question 1 I have the 1st and 2nd choices
& for 2nd question: 1st &3rd