We can use the sine law to find h. First, we determine the angle between the line of sight and h:

180 - 90 - 39 = 51 degrees

The sine law states that the ratio of one triangle's angle to the opposite side's length is the same as another angle to its opposite side's length, so we can solve for h as follows:

h/sin(39) = 500/sin(51)

h = 500*sin(39)/sin(51)

When we round to the nearest whole number, we get h = 405 ft.