There are 2 temples, one on each bank of the river, just opposite to each other. One of the temples A is 40 m high. As observed from the top of this temple A, the angle of depression of the top and the foot of the other temple B are 12∘30′ and 21∘48′ respectively. Find the height of the temple B in meters.
Use the angle of dec to the base of B to find the distance to B
tan 21.8 = 40/x x = 100.00713 meters (note the 21 degrees 48 min is 21.8 decimal degrees)
Now use the angle of dec to the top
tan 12.5 = 40/x x = 180.4283 meters this is the distance line to the to the triangle vertex which the top intercepts
but the top is only 100.00713 meters away
(180.428-100.00713)/ 180.428 * 40 = 17.829 meters high = temple B
Check tan 12.5 = 17.829/80.428 ....check !
