If sin x = 1/5 and cos x < 0, find sin (2x)

Answer 1

sinx = 1/5

cosx <0

5 = hypotenuse, 1 = opposite side, adjoining side = sqr(25-1) = sqr24 = 2sqr6

cosx = - 2sqr6/5

sin2x = 2sinxcosx = 2(1/5)(2/5)sqr6 = (4/25)sqr6 = about .392 = about 0.4

sinx =1/5, x = about 11.54

2x = about 23.08

sin23.08 = about ,392 = about 0.4