Answer:
Step-by-step explanation:
Equation for a hyperboloid of one sheet, with center at the origen and axis along z-axis is:
(x/a)²  +  (y/b)²   -  (z/c)²  =  1                         (1)
We have to find a , b, and c
We can express equation (1)
(x/a)²  +  (y/b)²    =  (z/c)² + 1                 (2)
Now if we cut the hyperboloid with planes parallel to xy plane we get for  z = k       ( K = 1 , 2 , 3  and so on ) circles of different radius
(x/a)²  +  (y/b)²    =  (k/c)² + 1
at z = k = 0 at the base of the hyperboloid  d = 300   or r = 150 m
we have 
(x/a)²  +  (y/b)²   = 1      
 x²  +  y²   =   a²                a² = (150)²       a = b = 150
and    x²  +  y²  = (150)² 
Now the other condition is at 200 m above the base d = 500 m   r = 250 m  minimum diameter then in equation (2)  we have:
(x/a)²  +  (y/b)²    =  (z/c)² + 1        
(1/a)² [ x² + y² ]  = (z/c)² + 1  
but   x²  +  y²  = r²    and in this case   r  =  250 m  then
(250)²/(150)²   =  (z/c)² + 1    ⇒ (62500/ 22500)  =  (200/c)² + 1
2,78  =  40000/c² + 1
2.78c²  =  40000  + c²
1.78c² = 40000
c²  =  40000/1.78
c²  = 22471.91
c = 149,91
Then we finally have the equation:
 x²/(150)²   + y² /(150)² - z²/149,91  = 1