Final answer:
The area to the rear of the car not seen in mirrors is known as a blind spot, which cannot always be eliminated through mirror adjustments. It requires drivers to shoulder check for safety.
Step-by-step explanation:
The area to the rear of the car not seen in mirrors is commonly referred to as a blind spot. While adjusting mirrors can minimize blind spots, they often cannot eliminate them entirely. This is why drivers are encouraged to perform shoulder checks before changing lanes. The reflected rays in the mirror give us an image, but this image is known as a virtual image because it cannot be projected onto a screen; it seems to originate from a point behind the mirror. The true nature of a blind spot in a driving context means that these areas require extra attention to maintain safety on the road.