A pile 4m high driven into the bottom of a lake is 1m above the `
`water . Determine the length of the shadow of the pile on the bottom of the lake if `
` the sun rays make an angle of `45^@` with the water surface . The refractive index`
` if water is `4/3`. `

Explanation

To solve the problem, we will follow these steps:

### Step 1: Understand the setup
We have a pile that is 4 meters high, with 1 meter above the water surface and 3 meters submerged. The sun's rays make a 45° angle with the water surface. We need to find the length of the shadow of the pile on the bottom of the lake.

### Step 2: Identify the points
Let:
- Point A be the top of the pile (4 m above the bottom of the lake).
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