To determine the quadrant of \( \theta \) given \( \cos \theta = 3\sqrt{2} \) and \( \tan \theta = -3\sqrt{3} \), we can analyze the signs of the trigonometric functions:
- Cosine: \( \cos \theta \) is positive.
- Tangent: \( \tan \theta \) is negative.
Now, we identify in which quadrants cosine is positive and tangent is negative:
- Quadrant I: \( \cos \theta > 0 \), \( \tan \theta > 0 \) (not applicable)
- Quadrant II: \( \cos \theta < 0 \), \( \tan \theta > 0 \) (not applicable)
- Quadrant III: \( \cos \theta < 0 \), \( \tan \theta < 0 \) (not applicable)
- Quadrant IV: \( \cos \theta > 0 \), \( \tan \theta < 0 \) (applicable)
Since \( \cos \theta \) is positive and \( \tan \theta \) is negative, \( \theta \) must be in Quadrant IV.
Therefore, the answer is:
Quadrant IV