# Finding the Cosine of Complex Number in Golang

Go language provides inbuilt support for basic constants and mathematical functions for complex numbers with the help of the cmplx package. You are allowed to find the cosine of the specified complex number with the help of the Cos() function provided by the math/cmplx package. So, you need to add a math/cmplx package in your program with the help of the import keyword to access the Cos() function.

Syntax:

`func Cos(y complex128) complex128`

Let us discuss this concept with the help of the given examples:

Example 1:

 `// Golang program to illustrate how to find ` `// the cosine value of the given complex number ` ` `  `package main ` ` `  `import ( ` `    ``"fmt"` `    ``"math/cmplx"` `) ` ` `  `// Main function ` `func main() { ` ` `  `    ``// Finding Cosine of the  ` `    ``// specified complex number ` `    ``// Using Cos() function ` `    ``res_1 := cmplx.Cos(2 + 5i) ` `    ``res_2 := cmplx.Cos(-1 + 8i) ` `    ``res_3 := cmplx.Cos(-1 - 7i) ` ` `  `    ``// Displaying the result ` `    ``fmt.Println(``"Result 1:"``, res_1) ` `    ``fmt.Println(``"Result 2:"``, res_2) ` `    ``fmt.Println(``"Result 3:"``, res_3) ` `} `

Output:

```Result 1: (-30.88223531891674-67.47278844058751i)
Result 2: (805.3093276729627+1254.19468537245i)
Result 3: (296.2569584411429-461.3921082367867i)
```

Example 2:

 `// Golang program to illustrate how to find ` `// the cosine value of the given complex number ` ` `  `package main ` ` `  `import ( ` `    ``"fmt"` `    ``"math/cmplx"` `) ` ` `  `// Main function ` `func main() { ` ` `  `    ``cnumber_1 := complex(1, 2) ` `    ``cnumber_2 := complex(3, 6) ` ` `  `    ``// Finding cosine ` `    ``cvalue_1 := cmplx.Cos(cnumber_1) ` `    ``cvalue_2 := cmplx.Cos(cnumber_2) ` ` `  `    ``// Sum of two cosine values ` `    ``res := cvalue_1 + cvalue_2 ` ` `  `    ``// Displaying results ` `    ``fmt.Println(``"Complex Number 1: "``, cnumber_1) ` `    ``fmt.Println(``"Cosine 1: "``, cvalue_1) ` ` `  `    ``fmt.Println(``"Complex Number 2: "``, cnumber_2) ` `    ``fmt.Println(``"Cosine 2: "``, cvalue_2) ` `    ``fmt.Println(``"Sum : "``, res) ` ` `  `} `

Output:

```Complex Number 1:  (1+2i)
Cosine 1:  (2.0327230070196656-3.0518977991518i)
Complex Number 2:  (3+6i)
Cosine 2:  (-199.6969662082171-28.465762393875067i)
Sum :  (-197.66424320119745-31.517660193026867i)
```

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