Program to Calculate the Perimeter of a Decagon in C program

A decagon is a polygon with 10 sides and 10 vertices. In a regular decagon, all sides are equal in length and each internal angle measures 144 degrees. The perimeter of any polygon is the sum of all its side lengths.

Syntax

Perimeter = 10 × side_length

Example: Calculate Decagon Perimeter

The following program calculates the perimeter of a decagon given the side length −

#include <stdio.h>

void calculatePerimeter(int side) {
    int perimeter = 10 * side;
    printf("Side length: %d<br>", side);
    printf("Perimeter of decagon: %d<br>", perimeter);
}

int main() {
    int side = 10;
    calculatePerimeter(side);
    
    printf("<br>");
    
    side = 20;
    calculatePerimeter(side);
    
    return 0;
}

Side length: 10
Perimeter of decagon: 100

Side length: 20
Perimeter of decagon: 200

Example: Using Float Values

For more precise calculations with decimal side lengths −

#include <stdio.h>

float calculatePerimeter(float side) {
    return 10.0 * side;
}

int main() {
    float side = 15.5;
    float perimeter = calculatePerimeter(side);
    
    printf("Side length: %.2f<br>", side);
    printf("Perimeter of decagon: %.2f<br>", perimeter);
    
    return 0;
}

Side length: 15.50
Perimeter of decagon: 155.00

Key Points

• A decagon has exactly 10 equal sides in its regular form
• The perimeter formula is simply: Perimeter = 10 × side_length
• Each internal angle in a regular decagon measures 144 degrees

Conclusion

Calculating the perimeter of a decagon is straightforward using the formula P = 10 × side_length. This simple multiplication works for both integer and floating-point side lengths.