Real numbers and rational numbers
The first (and most typical) way to find distance of two points is by using the distance formula.

One alternative is the Manhattan metric, also called the taxicab metric. This option is much more complicated, and rarely used in high school math. d(x,y)=∑i|xi-yi|
1st :The angle of depression 30° = the angle of elevation (from the truck to the height of the building.
2nd :
cos 30° = (adjacent side)/(hypotenuse)
cos 30° = x/100, but cos 30°= (√3)/2
(√3)/2 = x/100 and x = (100√3)/2
and x = (50.√3) = 86.60 m
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