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If sinA=5/13 for angle A in Quadrant I, find tan2A

0 votes

Double angles and half-angles

double-angle
half-angle-identity

asked Nov 26, 2013 in TRIGONOMETRY by skylar Apprentice

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1 Answer

0 votes

Sina = 5/13

From the pythogeron therom

Cosa = 12/13

Tana = 5/12

Sin2a = 2SinaCosa = 2*5/13*12/13 = 120/169

Cos2a = Cos^2a-Sin^2a =144/169-25/169 = 119/169

Tan2a = Sin2a/Cos2a

= (120/169)/(119/169)

= 120/119

answered Jan 21, 2014 by dozey Mentor

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