In today’s video, we will review some bare heights and distance information before moving on to the main topic. 

Height refers to the vertical measurement of an object. 

Distance is the horizontal between two points. 

Elevation Angle

Consider a situation where a person is on the ground and looking at an object at some height, such as the top of a building. In this case, the line of sight is the line that connects the man’s eye to the top of the building. The elevation angle comes from the line of sight and the horizontal line. 

The Depression Angle

In another case, a person appears standing at a certain height about an object.  The line o sight refers to the path that connects the man’s eye to the bottom of the building. A line of sight and a horizontal line from the angle of depression.

Now let the height of the building is 75m and two men are standing on point A and point B.

Suppose distance AD = xm and DB =ym.

In the right angle Δ ADC, CD/AD = tan 30°

= 75/x = 1/ √3 = x = 75√3m 

Now in right angle Δ CDB, CD/BD =  tan 60°

75/y = √3 = √3y = 75 = y = 75/ √3 = 75/√3 ×√3/√3 = 75√3/3= 25√3

Total distance x+y = 75√3 + 25√3 = 100√3m.