An isosceles trapezoid has base angles that measure 60° each. The upper base has length 16 and the altitude of the trapezoid has 6 square root 3. What is the perimeter of the trapezoid?

To find the perimeter of the trapezoid, we need to know the lengths of all sides.
Given that the trapezoid is isosceles, the non-parallel sides (legs) are congruent. Let's denote the length of each leg as \( l \).
Now, we can use the properties of the trapezoid to find the length of the legs.
Since the upper base has length 16 and the altitude is 6√3, we can use these values to find the length of each leg using the right triangle formed by the altitude, one leg, and half the difference in base lengths:
l² = (16/2)^2 + 6\sqrt{3})^2
l^2 = 64 + 108
l^2 = 172
l = sqrt{172}
l = 2\sqrt{43}
Now, we can find the perimeter:
p = 16 + 16 + 2(2\sqrt{43}) \]
p = 32 + 4\sqrt{43}
Therefore, the perimeter of the trapezoid is
(32 + 4\sqrt{43}).