Answer:
cos(β) = √6/3
Explanation:
Given β lies in the fourth quadrant and sin (β) = -√3/3
we know that the trigonometry formula
sin²(β)+cos²(β) = 1
cos²(β) = 1- sin²(β)
cos²(β) = 1- ( -√3/3)²
=

cos(β) = √6/9 = √6/3
we Know that β lies in the fourth quadrant so cos(β) is Positive
cos(β) = √6/3