Converting between degrees and radians
 The trigonometric operations and geometric manipulation are usually done in radians; it is always useful to be able to convert these into degrees and vice versa. show you some tips on how to handle the conversion between these units.
Create the radians.go file with the following content:
package main
import (
"fmt"
"math"
)
type Radian float64
func (rad Radian) ToDegrees() Degree {
return Degree(float64(rad) * (180.0 / math.Pi))
}
func (rad Radian) Float64() float64 {
return float64(rad)
}
type Degree float64
func (deg Degree) ToRadians() Radian {
return Radian(float64(deg) * (math.Pi / 180.0))
}
func (deg Degree) Float64() float64 {
return float64(deg)
}
func main() {
val := radiansToDegrees(1)
fmt.Printf("One radian is : %.4f degrees\n", val)
val2 := degreesToRadians(val)
fmt.Printf("%.4f degrees is %.4f rad\n", val, val2)
// Conversion as part
// of type methods
val = Radian(1).ToDegrees().Float64()
fmt.Printf("Degrees: %.4f degrees\n", val)
val = Degree(val).ToRadians().Float64()
fmt.Printf("Rad: %.4f radians\n", val)
}
func degreesToRadians(deg float64) float64 {
return deg * (math.Pi / 180.0)
}
func radiansToDegrees(rad float64) float64 {
return rad * (180.0 / math.Pi)
}
output:
sangam:golangdaily sangam$ go run radians.go
One radian is : 57.2958 degrees
57.2958 degrees is 1.0000 rad
Degrees: 57.2958 degrees
Rad: 1.0000 radians
How it works…

The Go standard library does not contain any package with a function converting radians to degrees and vice versa. But at least the Pi constant is a part of the math package, so the conversion could be done as shown in the sample code.

The preceding code also presents the approach of defining the custom type with additional methods. These are simplifying the conversion of values by handy API.