Respuesta :

Answer:

0.75m

Step-by-step explanation:

The volume of a prism is:

the area of the cross section × length

In this case the cross section is the circle so the formula is

v = πr²h

volume = 21m³

height or length = 12m

Sub in the values:

21 = πr² × 12

1.75 = πr² (I divided both sides by 12)

0.5570423008 = r² (I divided both sides by π)

r = 0.74635... (I square rooted both sides)

r ≈ 0.75m (to 2 d.p)