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How do you find the exact value of the expression sin 2x, cos 2x, and tan 2x given #Sin x = 12/13# where x lies on Quadrant I?

1 Answer

May 24, 2015

sin x = 12/13

#cos^2 x = 1 - sin^2 x = 1 - 144/169 = 25/169 -> cos x = 5/13#

#sin 2x = 2sin x.cos x = 2(12/13)(5/13) = (120)/(169) = 0/71 #

#cos 2x = 2cos^2 x - 1 = -119/169 = - 0.70#

#tan 2x = +- 0.71/-0.70 = - 1#

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