The longer leg of a 30°-60°-90° triangle is 18. What is the length of the other leg?

This is a special right triangle meaning that the 30 degrees matches with the smaller leg (x), 60 with the longer leg (x•square root of 3) and 90 matches with the hypotenuse (2x)

In this case 18 = x*square root of 3

x = 10.4 (rounded) smaller leg is 10.4 (x)