Ф is the angle of elevation to the topo of the building from G. length of leg adyacent to angle Ф=40m length of leg opposite to angle Ф=15 m tan Ф=leg opposite / leg adyacent=15/40=0.375 Ф=arctan 0.375=20.56º
The angle of elevation to the top of the building from G is 20.56º.
