If the height, curved surface area and the volume of a cone are h, c and V respectively, then 3πVh 3 - c 2 + 9V 2 will be equal to?

Let h be the height,
Volume of the cone = V
and curved surface area of the cone = c
∴ 1/3 πr²h = V, πrl = c
i.e., πr√r² + h² = c
π²r²(r² + h²) = c²
Consider 3πVh³ - c²h² + 9V²
= 3π x 1/3πr²h x h³ - π²r²(r² + h²)h + 9 x 1/9 x π²r⁴ h²
= π²r²h⁴ - π²r⁴h² - π²r²h⁴ + π²r⁴ = 0