Slant Height of a Cone
We are given a cone where the height BC = 6 in and the diameter is 4 in.
The radius is half the diameter, thus AB = 4/2 = 2 in
It's required to find the slant height of the cone, i.e., the value of AC.
Note ABC is a right triangle where the right angle is at vertex B. Thus the hypotenuse is AC and the legs are AB and BC.
Applying the Pythagorean's Theorem:

Substituting values:

Taking the square root:
![\begin{gathered} AC=\sqrt[]{40} \\ AC=\sqrt[]{4\cdot10} \\ AC=\sqrt[]{4}\cdot\sqrt[]{10} \\ AC=2\text{ }\sqrt[]{10} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/99hhazd9nya403z89bxpvmvfwpu4fuqvbv.png)