Rays of light are incident on a plane mirror at `40^@`. At what angle with the first should a second mirror be placed such that the rays emerge from the second mirror parallel to the first mirror.

Explanation

To solve the problem of determining the angle at which the second mirror should be placed so that the rays emerging from it are parallel to the rays incident on the first mirror, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Incident Angle**:
The rays of light are incident on the first plane mirror at an angle of \(40^\circ\) with respect to the mirror's surface.

2. **Determine the Angle with the Normal**:
...