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## 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..