Write a C program to receive Polar co-ordinates(r, θ) and convert them into Cartesian co-ordinates(x, y). Ask the user to enter theta(θ) value in degrees.
We can calculate area of circle if we know the value of its radius. So using that, we shall write the logic in c program to calculate the area of a circle, and we will us math.h library functions in this program.
printf("Area of circle is %f \n", (M_PI * pow(radius, 2)));
return 0;
}
#include < stdio.h >
#include < math.h >
int main()
{
float radius;
printf("Enter radius of circle\n");
scanf("%f", &radius);
printf("Area of circle is %f \n", (M_PI * pow(radius, 2)));
return 0;
}
Output: Enter radius of circle 2.0 Area of circle is 12.566371
Scanf(): For user input
In above c program we are asking user to enter the values for variable a and b. You can know more about scanf() method/function in this video tutorial: Using Scanf in C Program
Calculate Area of a Circle using math.h library: C
math.h library file has a constant M_PI which has the value of PI. Since it’s a constant variable we can not change its value in our program. We’re also using pow() method/function present in math.h header file.
Formula for calculating Area of a circle
Formula for calculating Area of a circle is PI * radius * radius. We take value of radius from user and using above formula calculate area of the circle and output result to the console window. Since we’re using math.h library file we use M_PI and pow() methods for the expression.