The Mathematical Symbol "Right Angle (∟)"
The "Right Angle" Symbol (∟)
The ∟ symbol represents a "right angle" in geometrical contexts. In Euclidean geometry, a right angle is an angle of exactly 90°, corresponding to a quarter of the full circle.
Usage of ∟
Right angles are a fundamental concept in geometry and trigonometry. Their properties have been understood and utilized since ancient times.
Example 1: In Rectangles
All four angles in a rectangle are right angles. Thus, if a quadrilateral has four right angles (as denoted by ∟), then it is a rectangle.
Example 2: Pythagoras' Theorem
In a right-angled triangle, the side opposite the right angle is called the hypotenuse. Pythagoras' theorem states that in a right-angled triangle, the square of the length of the hypotenuse is equal to the sum of the squares of the other two sides. If ∟ denotes the right angle, then the theorem can be represented as: c² = a² + b², where c is the length of the hypotenuse, and a and b are the lengths of the triangle's other two sides.
Significance in Different Fields
Right angles have a wide range of applications:
- Architecture: Right angles are crucial in construction, ensuring structures are perpendicular and stable.
- Mathematics: They're foundational in geometry, trigonometry, and calculus.
- Astronomy: Right angle triangles aid in calculations involving the distances and sizes of celestial bodies.
In summary, the ∟ symbol is a simple yet powerful representation of a concept that has been essential in various disciplines throughout history.
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Codes for the ∟ Symbol
| The Symbol | ∟ | |
| Alt Code | Alt 8735 | |
| HTML Code | ∟ | |
| HTML Entity | ∟ | |
| CSS Code | \221F | |
| Hex Code | ∟ | |
| Unicode | U+221F |
How To Insert the ∟ Symbol
(Method 1) Copy and paste the symbol.
The easiest way to get the ∟ symbol is to copy and paste it into your document.Bear in mind that this is a UTF-8 encoded character. It must be encoded as UTF-8 at all stages (copying, replacing, editing, pasting), otherwise it will render as random characters or the dreaded �.
(Method 2) Use the "Alt Code."
If you have a keyboard with a numeric pad, you can use this method. Simply hold down the Alt key and type 8735. When you lift the Alt key, the symbol appears. ("Num Lock" must be on.)(Method 3) Use the HTML Decimal Code (for webpages).
| HTML Text | Output |
|---|---|
| <b>My symbol: ∟</b> | My symbol: ∟ |
(Method 4) Use the HTML Entity Code (for webpages).
| HTML Text | Output |
|---|---|
| <b>My symbol: ∟</b> | My symbol: ∟ |
(Method 5) Use the CSS Code (for webpages).
| CSS and HTML Text | Output |
|---|---|
|
<style> span:after { content: "\221F";} </style> <span>My symbol:</span> | My symbol: ∟ |
(Method 6) Use the HTML Hex Code (for webpages and HTML canvas).
| HTML Text | Output |
|---|---|
| <b>My symbol: ∟</b> | My symbol: ∟ |
| JavaScript Text |
|---|
|
const x = "0x"+"E9" ctx.fillText(String.fromCodePoint(x), 5, 5); |
| Output |
∟ |
(Method 7) Use the Unicode (for various, e.g. Microsoft Office, JavaScript, Perl).
The Unicode for ∟ is U+221F. The important part is the hexadecimal number after the U+, which is used in various formats. For example, in Microsoft Office applications (e.g. Word, PowerPoint), do the following:| Type | Output |
|---|---|
| 221F [Hold down Alt] [Press x] | ∟ (The 221F turns into ∟. Note that you can omit any leading zeros.) |
| JavaScript Text | Output |
|---|---|
| let str = "\u221F" document.write("My symbol: " + str) | My symbol: ∟ |