Program to Convert Radian to Degree in C

Converting radians to degrees is a common mathematical operation in C programming. A radian is the standard unit for measuring angles in mathematics, while degrees are commonly used in everyday applications. The complete angle of a circle is 360 degrees or 2? radians.

Syntax

degree = radian × (180 / ?)

Where ? (pi) ? 3.14159 or can be approximated as 22/7.

Conversion Formula

The mathematical relationship between radians and degrees is −

degree = radian × (180/?)
where, ? = 3.14159

For example, if radian = 9.0, then degree = 9.0 × (180/3.14159) = 515.92357

Example: Using Function Approach

This example demonstrates how to convert radians to degrees using a dedicated function −

#include <stdio.h>
#define PI 3.14159

// Function for converting radian to degree
double convert(double radian) {
    return (radian * (180.0 / PI));
}

int main() {
    double radian = 9.0;
    double degree = convert(radian);
    printf("Radian: %.2lf<br>", radian);
    printf("Degree: %.5lf<br>", degree);
    return 0;
}

Radian: 9.00
Degree: 515.92357

Example: Direct Calculation

You can also perform the conversion directly without using a separate function −

#include <stdio.h>
#define PI 3.14159

int main() {
    double radian = 1.57; // ?/2 radians
    double degree = radian * (180.0 / PI);
    
    printf("%.2lf radians = %.2lf degrees<br>", radian, degree);
    return 0;
}

1.57 radians = 90.00 degrees

Key Points

• Use double data type for precise calculations
• Define PI as a macro for better accuracy: #define PI 3.14159
• Remember: 180 degrees = ? radians
• For very precise calculations, use math.h library's M_PI constant

Conclusion

Converting radians to degrees in C is straightforward using the formula: degree = radian × (180/?). Always use double precision for accurate results and consider using the math.h library for mathematical constants.