Answer: Lattice parameter, a = (4R)/(√3)
Step-by-step explanation: 
The typical arrangement of atoms in a unit cell of BCC is shown in the first attachment.
The second attachment shows how to obtain the value of the diagonal of the base of the unit cell.
If the diagonal of the base of the unit cell = x
(a^2) + (a^2) = (x^2)
x = a(√2)
Then, diagonal across the unit cell (a cube) makes a right angled triangle with one side of the unit cell & the diagonal on the base of the unit cell.
Let the diagonal across the cube be y
Pythagoras theorem,
(a^2) + ((a(√2))^2) = (y^2)
(a^2) + 2(a^2) = (y^2) = 3(a^2)
y = a√3
But the diagonal through the cube = 4R (evident from the image in the first attachment)
y = 4R = a√3
a = (4R)/(√3)
QED!!!
 
        
                    
             
        
        
        
70 palm trees are on that street
        
             
        
        
        
Answer:
Distance = 8.06
Step-by-step explanation:
We have to use the distance formula  .
.
 coordinates of the first point
 coordinates of the first point
 coordinates of the second point
 coordinates of the second point 
To solve, plug the appropriate values into the formula. 
 
 
 
        
             
        
        
        
Answer: The system consists of parallel lines
Step-by-step explanation:
Given system of lines :
  
 

Substitute  in
 in  ,  we get
,  we get
 , which is not true.
 , which is not true.
That means , system has no solution.
i.e. they are representing parallel lines. [Parallel lines do not intersect and hence they do not have solution.]
 
        
             
        
        
        
Answer:
b
Step-by-step explanation:
the volume (V) of a cone is calculated as
V =  πr²h ( r is the radius , h is the height )
πr²h ( r is the radius , h is the height )
here diameter = 12 , so r = 12 ÷ 2 = 6 and h = 22 , then
V =  π × 6² × 22
π × 6² × 22
    =  π × 36 × 22
π × 36 × 22
     =  π × 792 ( cancel 3 and 792 by 3 )
π × 792 ( cancel 3 and 792 by 3 )
     = π × 264
     ≈ 829.4 m³ ( to the nearest tenth )