Why did the Terminator shoot its own foot to escape the trap?

Question

In Terminator Salvation movie, a terminator gets caught in a trap so that it is dangling upside down.

Instead of shooting the cable holding it upside down, it shoots its own foot.

Why not shoot the cable, or pull itself up and release the cable around its foot?

Answer 1

In the official novelisation, we learn that the T-600, frustrated by its inability to shoot the cable, decided to aim for a larger target, its own foot.

On the street outside, the stymied T-600 fired twice at the cable that had wrapped around its right foot. Most shells missed the gleaming, slender target. Those that struck it glanced off. Responding to the overriding resolve of its pursuit programming, it proceeded to shoot off the restraining foot. Thus freed, it slammed into the pavement below with enough force and weight to buckle the old concrete.
Proceeding to right itself, it limped toward the entrance to the factory.

_{^{Terminator Salvation - Official Novelisation}}

In the film you see it aiming at the cable for a brief second before it starts blasting away at its foot.