In the above example, find the angle of incidence at face `AB`, so that emergent ray grazes along the face `AC'`.

Explanation

To find the angle of incidence at face AB, so that the emergent ray grazes along the face AC in an equilateral triangle prism with a refractive index of √2, we can follow these steps:

### Step 1: Understand the Geometry of the Prism
We have an equilateral triangle prism, where each angle is 60 degrees. The sides are labeled as AB, BC, and AC.

### Step 2: Identify the Conditions for Grazing Emergence
For the emergent ray to graze along face AC, it must make an angle of 90 degrees with the normal at that face. This means that the angle of refraction (R2) at face AC will be 90 degrees.

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