# Program to calculate Area Of Octagon

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An octagon is a polygon with eight sides. To calculate the area of octagon the following formula is used,

Area of octagon = ((a2*2) / *tan (22.5°)) = ((2*a*a)(1+√2))

Code Logic, The area of a polygon with eight side is calculated by using the above formula. The expression uses sqrt function to find the square root of 2. The value of expression is evaluated as a floating point value that is put into the float area variable.

## Example

Live Demo

#include <stdio.h>
#include <math.h>
int main(){
int a = 7;
float area;
float multiplier = 6.18;
printf("Program to find area of octagon \n");
printf("The side of the octagon is %d \n", a);
area = ((2*a*a)*(1 + sqrt(2)));
printf("The area of Enneagon is %f \n", area);
return 0;
}

## Output

Program to find area of octagon
The side of the octagon is 7
The area of Enneagon is 236.592926