# Thread: area of a circle

1. ## area of a circle

Code:
```/* Program 3: Write a program that reads in the radius of a circle and prints
the circle's diamater, circumference, and area. Use the constant
value 3.1459 fo pie. Do thes calculations in output statements.
*/

#include<stdio.h>
#include<math.h> // math library
#define PI 3.1416
int main(void)
{
float radius, diamater, circumference, area;

printf("Please enter the radius of your circle: ");
scanf("%f",&radius); //stores variable

diamater = radius*2;  // calculates radius
circumference = PI*diamater; // calculates circumference
area= (PI)*radius*(exp(2)); // to calculate exponent

printf("Diameter: %0.2f\n", diamater);
printf("Circumference: %0.2f\n", circumference);
printf("Circle Area: %0.2f\n", area);

return 0;
}```
I have problem with the math function. I want to have this for the formula area= PI*radius^2, so i decided to use the math.h with the exp function but something is wrong. Can some one help me, thanks for your help

2. Use the pow() function for exponents, although in your case it's probably easiest to simply put radius*radius.

3. ## Thanks

thanks SirNOt for helping me out.

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