SOLUTION: If cosA = 1/3 for angle A in Quadrant I, find cos2A.

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Question 1029665: If cosA = 1/3 for angle A in Quadrant I, find cos2A.
Answer by fractalier(6550) About Me  (Show Source):
You can put this solution on YOUR website!
By identity,
cos 2A = 2*(cos A)^2 - 1 = 2(1/3)^2 - 1 = 2/9 - 1 = -7/9