Find the EXACT value of cos (2A) if sin A = sqrt(19)/10. Assume A is a Quadrant I angle in standard position. cos (2A) =

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Guest May 16, 2015

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Best Answer

cos2A = 1 - 2sin^2A = 1 - 2(√19/10)^2 = 1 -2 (19/100) = 1- 38/100 = 62/100 =

31/50

CPhill May 16, 2015

CPhill · Answer 1 · 2015-05-16T02:59:06

cos2A = 1 - 2sin^2A = 1 - 2(√19/10)^2 = 1 -2 (19/100) = 1- 38/100 = 62/100 =

31/50