And where is the rest of question?
Sorry this is quite hard but will you answer any question from me and here is the answer 9x feet
Answer: a/c = 1
a/b = 1/2 => a = 1/2 .b
b/c = 2 => c = 1/2 .b
=> a/c = (1/2.b)/(1/2.b) = 1
Step-by-step explanation:

Actually Welcome to the Concept of the Surface Areas and Volumes.
Since, Volume of cone = 1/3 π r^2 h,
here, r = 10 Inches and h= 12 inches, also π =3.14
so, VOC = 1/3 π (10)^2 × (20)
VOC = 1/3(3.14)(100)(20)= 2093.33 inch^3
=> so the volume of the cone is 2093.33 cubic inches.
8 units
Circumference = pi * 2 * radius
50.24 = 3.14 * 2 * radius
50.24 = 6.28 * radius
8 = radius