Daniel is 50.0 meters away from a building. he observes that his line-of-sight to the tip of the building makes an angle of 63.0° with the horizontal. what is the height of the building?

Since his line of sight 63 degrees makes with the tip of the building

Tan63° =  height of building / Horizontal distance

tan63° =  Height / 50

50tan63° = Height

Height = 50tan63°

Height ≈ 50*1.9626

Height ≈ 98.13 m

Height of the building is ≈ 98.13 m. Mind you in solving for this height we have neglected the height of Daniel.

The height of building actually should be 98.13 m plus the height of Daniel. Since the 63° was measured from his eye level.