Answer:
x= - 2
Step-by-step explanation:
hello : 
note : the equation of the axis symmetry  for the parabola : y =ax²+bx+c
when :  a≠ 0 is : x=- b/2a
in this exercice : a=1  and b=10
so : x= -10/2 = -5
 
        
             
        
        
        
We can use the ratios for special triangles (see the attachment below). We'll be using the 45-45-90 triangle. We notice that side BC is equal to 

, and side AC (x using the special right triangle) is equal to 16. We can therefore say that side BC is equal to 

 ft
:)
 
        
        
        
A as let’s say we have an isosceles triangle two of the sides are the same but one of the sides usually the base us different . Therefore , for this question the sides will both be equal so both 6 and the base 12-different HOPE THIS HELPS (Brainly best answer pleasee )