Question:C program for area of circle 

#include <stdio.h>
#define PI 3.141
int main(){
  float r, a;
  printf("Radius: ");
  scanf("%f", &r);
  a = PI * r * r;
  printf("%f\n", a);
  return 0;
}

Question:C program for area of a triangle 

#include<stdio.h>
#include<math.h>

int main(){
   
    float a,b,c;
    float s,area;
   
    printf("Enter size of each sides of triangle");
    scanf("%f%f%f",&a,&b,&c);
   
    s = (a+b+c)/2;
    area = sqrt(s*(s-a)*(s-b)*(s-c));
   
    printf("Area of triangle is: %.3f",area);
   
    return 0;
}
Sample output:
Enter size of each sides of the triangle: 2 4 5
Area of triangle is: 3.800

Question:C program for area of equilateral triangle 

#include<stdio.h>
#include<math.h>

int main(){

    float a;
    float area;

    printf("Enter size of side of the equilateral triangle : ");
    scanf("%f",&a);

    area = sqrt(3)/4*(a*a);

    printf("Area of equilateral triangle is: %.3f",area);

    return 0;
}
Sample output:
Enter size of side of the equilateral triangle: 5
Area of equilateral triangle is: 10.825

Question:C program for area of right angled triangle 

#include<stdio.h>
int main(){
    float h,w;
    float area;

    printf("Enter height and width of the right angled triangle : ");
    scanf("%f%f",&h,&w);

    area = 0.5 * h * w;
    printf("Area of right angled triangle is: %.3f",area);
    return 0;
}
Sample output:
Enter height and width of the right angled triangle: 10 5
Area of right angled triangle is: 25.000

Question:C program for area of a rectangle 

#include<stdio.h>

int main(){

    float l,w;
    float area;

    printf("Enter size of each sides of the rectangle : ");
    scanf("%f%f",&l,&w);

    area = l * w;
    printf("Area of rectangle is: %.3f",area);

    return 0;
}
[b]Sample output:[b]
Enter size of each sides of the rectangle: 5.2 20
Area of rectangle is: 104.000

Question:C program for area of a trapezium 

#include<stdio.h>

int main(){

    float b1,b2,h;
    float area;

    printf("Enter the size of two bases and height of the trapezium : ");
    scanf("%f%f%f",&b1,&b2,&h);

    area = 0.5 * ( b1 + b2 ) * h ;
    printf("Area of trapezium is: %.3f",area);
    return 0;
}
Sample output:
Enter the size of two bases and height of the trapezium: 5 8 3
Area of trapezium is: 19.500

Question:C program for area of a cube 

#include<stdio.h>

int main(){

    float a;
    float surface_area,volume;

    printf("Enter size of any side of a cube : ");
    scanf("%f",&a);

    surface_area = 6 * (a * a);
    volume = a * a * a;

    printf("Surface area of cube is: %.3f",surface_area);
    printf("\nVolume of cube is : %.3f",volume);

    return 0;
}
Sample output:
Enter size of any side of a cube: 3
Surface area of cube is: 54.000
Volume of cube is: 27.000

Question:C program for area of a cuboids 

#include<stdio.h>
int main(){

    float w,l,h;
    float surface_area,volume,space_diagonal;

    printf("Enter size of width, length and height of a cuboids : ");
    scanf("%f%f%f",&w,&l,&h);

    surface_area = 2*(w*l + l*h + h*w);
    volume = w * l * h;
    space_diagonal = sqrt(w*w + l*l + h*h);

    printf("Surface area of cuboids is: %.3f",surface_area);
    printf("\nVolume of cuboids is : %.3f",volume);
    printf("\nSpace diagonal of cuboids is : %.3f",space_diagonal);

    return 0;
}
Sample output:
Enter size of width, length and height of cuboids: 5 10 4
Surface area of cuboids is: 220.000
Volume of cuboids is: 200.000
Space diagonal of cuboids is: 11.874

Question:C program for area of a cylinder 

#include<stdio.h>
#include<math.h>

int main(){

    float r,h;
    float surface_area,volume;

    printf("Enter size of radius and height of a cylinder : ");
    scanf("%f%f",&r,&h);

    surface_area = 2 * M_PI * r * (r + h);
    volume = M_PI * r * r * h;

    printf("Surface area of cylinder is: %.3f",surface_area);
    printf("\nVolume of cylinder is : %.3f",volume);

    return 0;
}
Sample output:
Enter size of radius and height of a cylinder: 4 10
Surface area of cylinder is: 351.858
Volume of cylinder is: 502.655

Question:Write a c program or code to find or calculate the volume and surface area of cone 

#include<stdio.h>
#include<math.h>

int main(){

    float r,h;
    float surface_area,volume;

    printf("Enter size of radius and height of a cone : ");
    scanf("%f%f",&r,&h);

    surface_area = M_PI * r * (r + sqrt(r*r + h*h));
    volume = (1.0/3) * M_PI * r * r * h;

    printf("Surface area of cone is: %.3f",surface_area);
    printf("\nVolume of cone is : %.3f",volume);

    return 0;
}
Sample output:
Enter size of radius and height of a cone: 3 10
Surface area of cone is: 126.672
Volume of cone is: 94.248