Geometry with Vanilla JavaScript

In this lesson, we will solve Geometry problems using JavaScript. On the bottom of the page you will find a code editor pre-loaded with the example problems followed by problems for you to try on your own!

Problem 1: Area

Susie Smith owns a landcare service. She charges \$0.02 per square foot. Elliot's yard is 100 feet by 150 feet. How much will Susie charge Elliot?

``````let length = 100; // length
let width = 150; // width
let area = 100 * 150;  // length * width
let price = .02 * area;

// format to USD
const formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
})

// print amount
console.log(formatter.format(price));
``````

Problem 2: Pythagorean Theorem

What is the length of the length of the hypotenuse in the diagra below?

``````// Problem 2: Pythagorean theorem
// a**2 + b**2= c**
a = 12;
let b =8;
let c = Math.sqrt((a ** 2) + (b ** 2));
console.log("Problem 2: " + c);``````

Problem 3: Supplimentry Angles

Angles a and b are supplimentry. Angle a is 120o. How many degrees is angle b?

``````// Problem 3: Supplmentry Angles
// suplimentry angles equal 180 degrees
let angle_a = 120;
let angle_b = 180 - angle_a;
console.log("Problem 3: Angle b is " + angle_b + " degrees");``````

Problem 4: Perimeter

Suzie Smith has been hired to place a fence around the perimeter of Carlos's yard. His yard is rectangular. It is 20 yards wide. It is 20% longer than it is wide. Suzie charges \$15 per yard of fencing. How much will Carlos pay?

``````let yard_length = 20;
let yard_width = 1.2 * 20;
let perimeter = (2 * yard_length) + (2 * yard_width);
let cost = 15 * perimeter;

// format to USD
const formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
});

console.log("Problem 4: " + formatter.format(cost));``````

Problem 5: Circumfrence

Shana has a circular yard and has hired Suzie Smith to put a fence around it. This is a custom job, so Suzie will charge \$22 per yard of fencing. If the diameter of Shana's yard is 15 yards, how much will the fence cost?

``````// Problem 5: Circumference
// Circumference = π × diameter
let diameter = 15;
let circumference = Math.PI * 15;
let custom_cost = 22 * circumference;

console.log("Problem 5: " + formatter.format(custom_cost));``````

Problem 6:

Diedra also has a circular yard and wants Suzie Smith to put up a fence. The custom cost per yard will also be \$22. Diedra has a garden inside her yard that is right-triangle shaped. See the diagram below. One side of the garden is the radius of Diedra's yard. Another side of her garden measures 3 yards. The hypotenuse of her garden measures 5 yards. How much will a custom fence around Diedra's yard cost?

``````// Problem 6: Right Triangle in Circle
let side_b = 3;
let hypot = 5;
// radius**2 + b**2 = hypot**2
// radius**2 = hypot**2 - side_b**2
// radius = sqrt(hypot**2 - side_b**2)
let radius = Math.sqrt(hypot**2 - side_b**2);
// circumference = 2 * r *  π
let yard_circumference = 2 * radius * Math.PI;
// circumference * price per yard
let fence_cost = yard_circumference * 22;

console.log("Problem 6: " + formatter.format(fence_cost));``````

Run the Code

Run the code above in the editor below to observe the output.

Geometry with JavaScript Practice Problems

Now it's your turn to give it a try! Write JavaScript code to solve the following Geometry problems.

(1) Area

Mario is buying new carpet for his den. The carpet he picked out costs \$22 per square foot. Mario's den is rectangular. It is 12 feet wide and 20 feet long. How much will the carpet cost Mario?

(2) Circumference

Ellen has a circular mirror. She wants to put decrotive trim around the circumference of her mirror. If the mirror's radius is 12 inches, how many inches of decortive trim does Ellen need?

(3) Angles

Line b is a striaght verticle line. Line a intersects line b. Look at the diagram below. Given angle x is equal to 135o, solve for angles y and z.

(4) Right Triangle

A right triangle has 2 sides and a hypotenuse. The first two size measure 4 inches and 6 inches. What is the length of the hypotenuse?