C program to find perimeter, semi perimeter, and area of a triangle

Program to find perimeter, semi perimeter, and area of a triangle:

By Ahmad Irshad | Programming Exercises and Solutions > find perimeter, semi-perimeter, & area of a triangle in C

Write a C program to find perimeter, semi-perimeter, and area of a triangle if all sides are given. Let's have a look at the below logic.

Area of a triangle if all sides are given:

Farmula to be used:

1. perimeter = a + b + c
2. s = (a + b + c) / 2 // where s represent semi-perimeter
3. area = sqrt(s*(s-a)*(s-b)*(s-c)) // Where a, b, and c are the sides of a triangle.

Required knowledge for this exercise is: 

Basic Input output, Data Type, Arithmetic operators 

Before writing any program you just imagine about output screen first. For example, what input to be given, and output to be displayed. Let's have a look at the below example: 

INPUT:

Enter three sides of a triangle = 5, 6, 7

OUTPUT:

Perimeter of a triangle = 18.00 units

Semi-perimeter of a triangle = 9.00 units

Area of a triangle = 14.70 sq. units

Logic to find perimeter, semi-perimeter, & area of a triangle:

Step by step logic to find any angle of a triangle.

1) Print a massage to the user like "Enter all sides of a triangle:" using printf();

2) Input three sides of a triangle from user and store it in variables a, b, and c using scanf();

3) Now find perimeter, semi-perimeter & area of a triangle using below farmula

perimeter = a + b + c;  s = (a + b + c) / 2; and area = sqrt(s*(s-a)*(s-b)*(s-c));

4) At last print the value of perimeter, s, & area. that's it!

Program to find perimeter, semi-perimeter and area of a triangle if all sides are given: 

1. /* C program to find perimeter, semi-perimeter, & area of a triangle */ #include <stdio.h> #include <math.h>
2. int main() { double a, b, c, perimeter, s, area; /* Input three sides of a triangle from user */ printf("\nEnter three sides of a triangle: "); scanf("%lf%lf%lf", &a, &b, &c); /* You can find perimeter, semi-perimeter, & area of a triangle.
3. * by using follwing farmula:
4. * perimeter = a + b + c | semi-perimeter = (a + b + c) / 2
5. * area = sqrt(s*(s-a)*(s-b)*(s-c)) | where s is semi-perimeter.
6. */ perimeter = a + b + c;
7. s = (a + b + c)/2;
8. area = sqrt(s*(s-a)*(s-b)*(s-c));
9. /* Print values of perimeter, s, and area */ printf("Perimeter of triangle = %.2lf units\n", perimeter); printf("Semi-perimeter of triangle = %.2lf units\n", s);
10. printf("Area of a triangle = %.2lf sq. units\n", area);
11. return 0; }

%.2lf is used to print real values only up to 2 decimal places. You can also use %lf to print up to 12 decimal places by default.

Output:

1. Enter three sides of a triangle = 5, 6, 7
2. Perimeter of a triangle  = 18.00 units
3. Semi-perimeter of a triangle = 9.00 units
4. Area of a triangle = 14.70 sq. units

Next topic >> Arithmatic Operator.

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