Answer:
x  12
 12
[12,∞]
Step-by-step explanation:
 
        
                    
             
        
        
        
Answer:
The angle of elevation is approximately 
Step-by-step explanation:
Notice that the two pieces of information given: "400 ft away from a building", and building that is "850 ft tall", can be regarded as the two legs of a right angle triangle (see attached image).
Then the angle  that we are trying to find (the angle of elevation) can be found by using the arc-tangent function:
 that we are trying to find (the angle of elevation) can be found by using the arc-tangent function:

 
        
             
        
        
        
the radius is d/2. r=41/2 r=20.5
Step-by-step explanation: