To find the length of the cone, we usually refer to the slant height (l) when speaking about the length in the context of a cone. If you have a cone with a height (h) of 4 cm and a radius (r) of 2 cm, you can use the Pythagorean theorem to find the slant height.
The formula is:
\[ l = \sqrt{h^2 + r^2} \]
Plugging in the values:
\[ l = \sqrt{(4 , \text{cm})^2 + (2 , \text{cm})^2} \] \[ l = \sqrt{16 , \text{cm}^2 + 4 , \text{cm}^2} \] \[ l = \sqrt{20 , \text{cm}^2} \] \[ l = \sqrt{20} , \text{cm} \] \[ l = 2\sqrt{5} , \text{cm} \]
If you need the approximate numerical value, \( 2\sqrt{5} \) is about \( 4.47 , \text{cm} \).
Therefore, the length of the cone (slant height) is approximately 4.47 cm. If you meant a different length, please clarify!