If points $A$, $B$, and $C$ are collinear and in order along the same straight line, the length of $AC$ is simply the sum of $AB$ and $BC$, as the points form a single segment.

$AC = AB + BC$

Substitute the values:

$AC = 8 + 3 = 11$

Thus, the length of $AC$ is $\mathbf{11}$.

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Related Questions:

1. What if $AB = 8$ and $BC = 3$, but $B$ is between $A$ and $C$?
2. How would the calculation change if the points were not collinear?
3. If $A$, $B$, and $C$ are coordinates in 3D space, how would you calculate $AC$?
4. What is the significance of collinearity in geometry?
5. How do you represent points and distances in a coordinate system?

Tip: Always verify the order of points when calculating distances to ensure accuracy.