How wide is approximately 30 centimeters in the rearview mirror?

[MacEmmanuel]

When taking a driving test, the 30-centimeter distance from the rearview mirror appears roughly the width of two fingers in the mirror's view. In addition to observing the rearview mirror, here are some techniques: 1. Observe the wiper protrusion: From the driver's seat, when the protruding part of the wiper aligns with the right-side line, the distance is approximately 30 centimeters. 2. Look at the one-third point of the car's front: When the one-third point (on the right side) of the car's front aligns with the right-side line, the distance is exactly 30 centimeters. 3. Check the right front door handle: Observe the right front door handle in the right rearview mirror; if it is tangent to the right-side line, the distance is correct. If it's too far, slight adjustments to the steering are needed. If it's too close, there's a risk of crossing the line.