Question

The length of a shadow of a building is 28m. The distance from the top of the building to the shadow is 38m. Find the height of the building

Answer 1

It appears that the Pythagorean theorem can be applied to this problem
  (distance to shadow)² = (height of building)² + (length of shadow)²
  (38 m)² = (height of building)² + (28 m)²
  660 m² = (height of building)²
Then the height of the building is
  height of building = √660 m ≈ 25.7 m