Answer:
A
Step-by-step explanation:
Heron's formula finds the area of any triangle.
Area = sqrt(s*(s - a)*(s-b)*(s-c) )
s = (a + b + c)/2
a = 8
b = 16
c = 12
s = 36/2 = 18
s-a = 18 - 8 = 10
s-b = 18 - 16 = 2
s-c = 18 - 12 = 6
Area = sqrt(18*10*2*6) = sqrt(2160)
Area = 12*sqrt(15)
Area = 46.4758
Now x is easily found. It is the altitude to 16
Area = 1/2 16 * h
46.4758 * 2 / 16 = h
h = 3*sqrt(15)/2
h= 5.81
