Question

Se 0º e cos^4x - sen^4x = 7/75
Então calcule o sen x

Answer 1

sen²x+cos²x=1
cos²x=1-sen²x, 
assim cos$^{4}x$-sen$^{4}x$=7/75
cos²x.cos²x-sen²x.sen²x=7/75
(1-sen²x).(1-sen²x)-sen²x.sen²x=7/75
1-2sen²x+sen^4x-sen²x.sen²x=7/75
-2sen²x+sen²x.sen²x-sen²x.sen²x=(7/75)-1
-2sen²x=-69/75 *(-1)
2sen²x=69/75
sen²x=23/50
senx=√23/50