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Using the double angle formula, how do you find the function values for #cos^2(pi/12) and sin^2(pi/8)#?

1 Answer

Apr 30, 2015

Use the trig identities: #cos 2a = 2.cos^2 a - 1# and
#cos 2a = 1 - 2.sin^2 a#.

#2.cos^2 (Pi/12) = 1 + cos (Pi/6) = 1 + (sqr3)/2 = 1.866.#

#cos^2 (Pi/12) = 1.866/2 = 0.933 #

#2.sin^2 (Pi/8) = 1 - cos (Pi/4) = 1 - (sqr2)/2 = 0.293#

#sin^2 (Pi/8) = 0.147.#

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