Angle A is acute. I have a list of trig formulas here is the problem... 19. If sin A = 5/13, find sin 2A and cos 2A
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Originally Posted by RaphaelB30 Angle A is acute. I have a list of trig formulas here is the problem... 19. If sin A = 5/13, find sin 2A and cos 2A $\displaystyle \cos(2A) = 1 - 2\sin^2{A}$ $\displaystyle \sin(2A) = 2\sin{A}\cos{A}$ ... use a reference triangle or the Pythagorean identity to find $\displaystyle \cos{A}$
Originally Posted by RaphaelB30 Angle A is acute. I have a list of trig formulas here is the problem... 19. If sin A = 5/13, find sin 2A and cos 2A sin(x) = opp/hyp so you construct a right angled triangle with the opposite 5 and hypotenuse 13. You can then find the adjacent side easily enough and thus find cos(x). For sin(2A) and cos(2A) use an identity
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