Respuesta :

Imagine the shadow and the building height forms a right angle triangle; 

We know the height and the shadow make up the "legs" of the triangle, 

a²+b²=c²
(750)²+(111)²=c²
562500+12321=c²
574821=c²
c=√574821 
c=758.169 ≈ 758.2 ft 

Hope I helped :)