- #1
terryds
- 392
- 13
Homework Statement
If ##cos^3x+\frac{1}{cos^3x} = 0##, then sin 2x equals ...
A. -1
B. -√3
C. -√2
D. 1
E. 2
Homework Equations
Basic trigonometry
The Attempt at a Solution
[/B]
Let y = cos^3 x
y+1/y = 0
y^2 + 1 = 0
y = √(-1)
Then, I don't know what to do.. Help please..