Respostas

2013-11-28T20:17:49-02:00
Sen²x + cos²x = 1
sen²x + (-3/5)² = 1
sen²x + 9/25 = 1
sen²x = 1 - 9/25
sen²x = 25/25 - 9/25
sen²x = 16/25
sen x = \/(16/25)
sen x = 4/5

5 . (4/5)² - 3. senx/cosx = 
5. 16/25 - 3. 4/5 . (-5/3) = 
15/5 - (-60/15) = 
3 - (-4) = 3+4 = 7