# Distance between two points travelled by a boat

Write a program to determine the distance(D) between two points traveled by a boat, given the speed of boat in still water(B), the speed of the stream(S), the time taken to row a place and come back i.e T.

Examples:

```Input : B = 5, S = 1, T = 1
Output : D = 2.4

Input : B = 5, S = 2, T = 1
Output : D = 2.1
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Formula for distance is D = T*(B^2 – S^2)/ (2*B)

How does this formula work?

```Time taken when person goes upstream,
t1 = D/(B-S)
Time taken when person goes downstream,
t2 = D/(B+S)

We are given t1 + t2 = T
So, D/(B-S) + D/(B+S) = T
D = T*(B^2 - S^2)/ (2*B)
```

## C++

 `// CPP program to find distance between ` `// two points using boat speed, stream ` `// speed and total time. ` `#include ` `using` `namespace` `std; ` ` `  `// Function to calculate the distance ` `// between two points via boat ` `float` `distance(``float` `T, ``float` `B, ``float` `S) ` `{ ` `    ``return` `(T * (((B * B) - (S * S)) / (2 * B))); ` `} ` ` `  `int` `main() ` `{ ` `    ``// Time taken time taken to row a place  ` `    ``// and come back in hr ` `    ``float` `T = 1; ` ` `  `    ``// Speed of boat in still water in km/hr ` `    ``float` `B = 5; ` ` `  `    ``// Speed of stream in km/hr ` `    ``float` `S = 1; ` `    ``cout << ``"The distance between two points via boat = "` `         ``<< distance(T, B, S) << ``" km"``; ` `    ``return` `0; ` `} `

## Java

 `// java program to find distance between ` `// two points using boat speed, stream ` `// speed and total time. ` `import` `java.io.*; ` ` `  `class` `GFG { ` ` `  `    ``// Function to calculate the distance ` `    ``// between two points via boat ` `    ``static` `float` `distance(``float` `T, ``float` `B, ``float` `S) ` `    ``{ ` `        ``return` `(T * (((B * B) - (S * S)) / (``2` `* B))); ` `    ``} ` `     `  `    ``// Driver code ` `    ``public` `static` `void` `main (String[] args)  ` `    ``{ ` `        ``// Time taken time taken to row a place  ` `        ``// and come back in hr ` `        ``float` `T = ``1``; ` `     `  `        ``// Speed of boat in still water in km/hr ` `        ``float` `B = ``5``; ` `     `  `        ``// Speed of stream in km/hr ` `        ``float` `S = ``1``; ` `        ``System.out.println(``"The distance between two points via boat = "` `                           ``+ distance(T, B, S) + ``" km"``); ` `         `  `    ``} ` `} ` ` `  `// This code is contributed by vt_m. `

## Python 3

 `# Python 3 program to find distance  ` `# between two points using boat speed,  ` `# stream speed and total time. ` ` `  `# Function to calculate the distance ` `# between two points via boat ` `def` `distance( T, B, S): ` ` `  `    ``return` `(T ``*` `(((B ``*` `B) ``-` `(S ``*` `S)) ``/` `(``2` `*` `B))) ` ` `  `# Driver Code ` `if` `__name__ ``=``=` `"__main__"``: ` `     `  `    ``# Time taken time taken to row  ` `    ``# a place and come back in hr ` `    ``T ``=` `1` ` `  `    ``# Speed of boat in still  ` `    ``# water in km/hr ` `    ``B ``=` `5` ` `  `    ``# Speed of stream in km/hr ` `    ``S ``=` `1` `    ``print``(``"The distance between two "``+`  `          ``"points via boat ="``,  ` `           ``distance(T, B, S), ``"km"``) ` ` `  `# This code is contributed  ` `# by ChitraNayal `

## C#

 `// C# program to find distance between ` `// two points using boat speed, stream ` `// speed and total time. ` `using` `System; ` ` `  `class` `GFG { ` ` `  `    ``// Function to calculate the distance ` `    ``// between two points via boat ` `    ``static` `float` `distance(``float` `T, ``float` `B, ``float` `S) ` `    ``{ ` `        ``return` `(T * (((B * B) - (S * S)) / (2 * B))); ` `    ``} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `Main() ` `    ``{ ` `        ``// Time taken time taken to row a place ` `        ``// and come back in hr ` `        ``float` `T = 1; ` ` `  `        ``// Speed of boat in still water in km/hr ` `        ``float` `B = 5; ` ` `  `        ``// Speed of stream in km/hr ` `        ``float` `S = 1; ` `        ``Console.WriteLine(``"The distance between two points via boat = "` `+ ` `                                              ``distance(T, B, S) + ``" km"``); ` `    ``} ` `} ` ` `  `// This code is contributed by vt_m. `

Output:

```The distance between two points via boat = 2.4 km
```

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