Answer :
The original formula for the volume of a cone is
[tex]V=\dfrac{1}{3}\pi r^2h[/tex]
O.K. You give the approximate value of pi in the formula.
[tex]V=\dfrac{1}{3}\cdot3.14r^2h[/tex]
We have:
[tex]V=66\ cm^3,\ r=3\ cm[/tex]
Substitute:
[tex] \dfrac{1}{3}\cdot3.14\cdot3^2h=66\\\\3.14\cdot3h=66\\\\9.42h=66\ \ \ \ |:9.42\\\\h\approx7\ cm [/tex]
Answer: 7 cm.