State two uses of a plane mirror.

Explanation

### Step-by-Step Solution:

1. **Identify the Question**: The question asks for two uses of a plane mirror.

2. **First Use**: One common use of a plane mirror is in barbershops. Barbers use plane mirrors to allow customers to see their own faces while getting a haircut or grooming. This helps customers check their appearance from different angles.

3. **Second Use**: Another important use of a plane mirror is in periscopes. Periscopes are devices that allow a person to see objects that are not in their direct line of sight, often used in submarines or by soldiers. They utilize two plane mirrors positioned at an angle to reflect light from an object above an obstacle to the viewer's eye.

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