Step-by-step explanation: Notice that we have a 30° angle and we're given that the side opposite the 30° angle has a length of h and the side adjacent to the 30° angle has a length of 18.
Remember than
so we can setup the equation tan 30° = h/18.
Solving for h, we multiply both sides of the
equation by 18 and we have (18)(tan 30°) = h.
From here, we enter this into our calculator to get 10.3923 or 10.4.
Instead of using trigonometry here, we could have also noticed that this is a special right triangle, a 30° - 60° - 90° triangle, which means that the long leg is √3 times the length of the short leg, so we could have setup an equation to find the value of h. Either way should be acceptable.