Find the Area of a Triangle in C

Introduction

In this lab, you will learn how to calculate the area of a triangle using C programming. The lab consists of three main steps: reading the base and height of the triangle, computing the area using the formula Area = 0.5 _ Base _ Height, and printing the calculated area. By the end of this lab, you will have a solid understanding of how to perform basic geometry calculations in C.

Skills Graph

Read Base and Height

In this step, you will learn how to read the base and height of a triangle using C programming. We'll create a simple program that allows user input for the triangle's dimensions.

First, let's create a new C file in the project directory:

cd ~/project
nano triangle_area.c

Now, enter the following code to read base and height:

#include <stdio.h>

int main() {
    float base, height;

    // Prompt user to enter base
    printf("Enter the base of the triangle: ");
    scanf("%f", &base);

    // Prompt user to enter height
    printf("Enter the height of the triangle: ");
    scanf("%f", &height);

    // Print the input values
    printf("Base: %.2f\n", base);
    printf("Height: %.2f\n", height);

    return 0;
}

Example output:

Enter the base of the triangle: 5.5
Enter the height of the triangle: 4.2
Base: 5.50
Height: 4.20

Let's break down the code:

• We use float to store decimal numbers for base and height
• printf() is used to display prompts to the user
• scanf() reads the user's input for base and height
• %.2f formats the output to show two decimal places

Compile the program:

gcc triangle_area.c -o triangle_area

Example output:

(no output if compilation is successful)

Run the program:

./triangle_area

Compute Area = 0.5 _ Base _ Height

In this step, you will learn how to calculate the area of a triangle using the formula: Area = 0.5 _ Base _ Height. We'll modify the previous program to compute and display the triangle's area.

Open the existing file:

cd ~/project
nano triangle_area.c

Update the code to calculate the area:

#include <stdio.h>

int main() {
    float base, height, area;

    // Prompt user to enter base
    printf("Enter the base of the triangle: ");
    scanf("%f", &base);

    // Prompt user to enter height
    printf("Enter the height of the triangle: ");
    scanf("%f", &height);

    // Calculate area
    area = 0.5 * base * height;

    // Print input values and calculated area
    printf("Base: %.2f\n", base);
    printf("Height: %.2f\n", height);
    printf("Area of the triangle: %.2f\n", area);

    return 0;
}

Compile the updated program:

gcc triangle_area.c -o triangle_area

Example output:

(no output if compilation is successful)

Run the program:

./triangle_area

Example output:

Enter the base of the triangle: 5.5
Enter the height of the triangle: 4.2
Base: 5.50
Height: 4.20
Area of the triangle: 11.55

Let's break down the area calculation:

• We added a new float variable area
• The formula area = 0.5 * base * height calculates the triangle's area
• printf() displays the calculated area with two decimal places

Print the Area

In this final step, we'll enhance the program to provide a more user-friendly output and format the area printing.

Open the existing file:

cd ~/project
nano triangle_area.c

Update the code to improve area printing:

#include <stdio.h>

int main() {
    float base, height, area;

    // Prompt user to enter base
    printf("Triangle Area Calculator\n");
    printf("----------------------\n");
    printf("Enter the base of the triangle: ");
    scanf("%f", &base);

    // Prompt user to enter height
    printf("Enter the height of the triangle: ");
    scanf("%f", &height);

    // Calculate area
    area = 0.5 * base * height;

    // Print formatted output
    printf("\nCalculation Results:\n");
    printf("-------------------\n");
    printf("Base:   %.2f\n", base);
    printf("Height: %.2f\n", height);
    printf("Area:   %.2f square units\n", area);

    return 0;
}

Compile the updated program:

gcc triangle_area.c -o triangle_area

Example output:

(no output if compilation is successful)

Run the program:

./triangle_area

Example output:

Triangle Area Calculator
----------------------
Enter the base of the triangle: 6.0
Enter the height of the triangle: 4.0

Calculation Results:
-------------------
Base:   6.00
Height: 4.00
Area:   12.00 square units

Key improvements:

• Added descriptive headers for input and output
• Formatted output with clear labels
• Added "square units" to clarify the area measurement
• Improved readability with consistent formatting

Summary

In this lab, you will learn how to read the base and height of a triangle using C programming, and then calculate the area of the triangle using the formula: Area = 0.5 _ Base _ Height. The program prompts the user to enter the base and height, and then computes and displays the triangle's area.

The key learning points are: 1) using printf() to display prompts to the user, 2) using scanf() to read the user's input for base and height, 3) calculating the area using the formula Area = 0.5 * Base * Height, and 4) formatting the output to show two decimal places.