Question

the figure shows that the angle of elevation to the top of the building changes from 20 degree to 40 degree as an observer advances 75 feet toward the building. Find the height of the building to the nearest feet.

Answer 1

Assume the observer started out x feet from the building

tan 20 = h/x
tan 40 = h/(x-75)

.3639 = h/x
.8390 = h/(x-75)

h = .3639x
so
.8390 = .3639x/(x-75)

x = 132.45
h = 48.20

Answer 2

the figure shows that the angle of elevation to the top of the building changes from 20 degree to 40 degree as an observer advances 75 feet toward the building. Find the height of the building to the nearest feet.