JavaScript: Check whether a point lies strictly inside a given circle

JavaScript Basic: Exercise-120 with Solution

Check if Point is Inside Circle

Write a JavaScript program to check if a point lies strictly inside the circle.

Input:
Center of the circle (x, y)
Radius of circle: r
Point inside a circle (a, b)

Sample Solution:

JavaScript Code:

// Function to check if a point (a, b) is inside a circle with center (x, y) and radius r
function check_a_point(a, b, x, y, r) {
    // Calculate the squared distance between the center of the circle (x, y) and the point (a, b)
    var dist_points = (a - x) * (a - x) + (b - y) * (b - y);
    
    // Square the radius for comparison
    r *= r;
    
    // Check if the squared distance between points is less than the squared radius
    if (dist_points < r) {
        return true; // Point is inside the circle
    }
    return false; // Point is outside the circle or on the circle
}

// Test cases
console.log(check_a_point(0, 0, 2, 4, 6)); // Output: true (Point (0,0) is inside the circle with center (2,4) and radius 6)
console.log(check_a_point(0, 0, 6, 8, 6)); // Output: false (Point (0,0) is outside the circle with center (6,8) and radius 6) 

Output:

true
false

Live Demo:

See the Pen javascript-basic-exercise-120 by w3resource (@w3resource) on CodePen.

Flowchart:

ES6 Version:

// Function to check if a point (a, b) is inside a circle with center (x, y) and radius r
const check_a_point = (a, b, x, y, r) => {
    // Calculate the squared distance between the center of the circle (x, y) and the point (a, b)
    const dist_points = (a - x) ** 2 + (b - y) ** 2;
    
    // Square the radius for comparison
    r **= 2;
    
    // Check if the squared distance between points is less than the squared radius
    if (dist_points < r) {
        return true; // Point is inside the circle
    }
    return false; // Point is outside the circle or on the circle
}

// Test cases
console.log(check_a_point(0, 0, 2, 4, 6)); // Output: true (Point (0,0) is inside the circle with center (2,4) and radius 6)
console.log(check_a_point(0, 0, 6, 8, 6)); // Output: false (Point (0,0) is outside the circle with center (6,8) and radius 6)

For more Practice: Solve these Related Problems:

• Write a JavaScript program that determines if a given point lies strictly inside a circle using the distance formula.
• Write a JavaScript function that calculates the distance between a point and a circle’s center and checks it against the radius.
• Write a JavaScript program that validates input coordinates and returns true if the point is inside the circle, false otherwise.

Go to:

• JavaScript basic Exercises Home ↩
• JavaScript Exercises Home ↩

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