Respostas

2014-04-03T19:02:51-03:00
Sen 2x = 2.sen x. cos x
sen 2x = 2.3/5.4/5
sen 2x = 24/25

cos 2x = cos²x - sen²x
cos 2x = (4/5)² - (3/5)²
cos 2x = 16/25 - 9/25
cos 2x = 7/25

tg x = sen x / cos x
tg x = 3/5 / 4/5
tg x = 3/4
tg 2x = 2.tg x / 1-tg x²
tg 2x = 2.3/4 / 1 - (3/4)²
tg 2x = 3/2 / 1 - 9/16
tg 2x = 3/2 / 7/16
tg 2x = 3/2 . 16/7
tg 2x = 48/14
tg 2x = 24/7
2 5 2