For this, you just have to remember that the volume of a cone is 1/3hπr² (1/3 times pi times the radius squared). Our volume is 12π, so we plug in 12π into our formula, as well as our height of 4 inches, to solve for the radius, like so:
12π=(1/3)(4)πr²
Now we just do the rest of the math.
12π=(1/3)(4)πr²
12=(1/3)(4)r² (divide both sides by π)
3=1/3r² (divide both sides by 4)
9=r² (divide both sides by 1/3)
3=r (take the square root of both sides).
Therefore, the radius of the cone is 3.
