Which command is used to make a sketch segment size and angle fixed, preventing changes?

The command used to make a sketch segment size and angle fixed, preventing changes, is the "Lock" command. When a segment is locked, it is essentially secured in its current dimension and angle, ensuring that no modifications can be made inadvertently while editing the sketch. This is particularly useful in parametric design, where maintaining certain dimensions and angles is critical for the integrity of the overall design.

The "Fix" command is often associated with setting a specific point or element in place, but it might not specifically apply to locking dimensions or angles like the Lock command does. "Constraint" allows you to define relationships between sketch entities, which is vital in managing how they interact but does not specifically 'lock' their size or angle. Lastly, "Anchor" typically refers to attaching components to a specific point or location within a sketch, which does not provide the same functionality as locking a dimension. Thus, the Lock command distinctly fulfills the requirement of preventing changes to a segment's size and angle.