A boatman finds that he can save `6 s` in crossing a river by the quickest path than by the shortest path. If the velocity of the boat and the river be, respectively, `17 ms^-1 and 8 ms^-1`, find the river width.

Explanation

To solve the problem, we will analyze the situation step by step.

### Step 1: Understand the Problem
We need to find the width of the river (D) given that the boatman saves 6 seconds by taking the quickest path compared to the shortest path. The speed of the boat (Vb) is 17 m/s and the speed of the river (Vr) is 8 m/s.

### Step 2: Define the Times for Both Paths
1. **Quickest Path (T1)**: The quickest path is when the boatman aims upstream at an angle to counteract the river's current. The effective speed of the boat can be calculated using the Pythagorean theorem:
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