
How to Find the Value of Root 2 with Proof and Examples
The concept of value of root 2 is widely used across geometry, algebra, trigonometry and even in daily life calculations. Understanding the value of root 2 helps in solving questions about squares, diagonals, surds, and much more, making it a vital part of maths learning for students of all levels.
What Is Value of Root 2?
The value of root 2 (written as √2 or √2) means “the number which, when multiplied by itself, gives 2.” In maths, the value of root 2 is about 1.41421356… and goes on without ending or repeating, which makes it an irrational number. You’ll find this concept applied in areas such as geometry (diagonal of a square), trigonometry (sin 45°, cos 45°), and algebra (solving quadratic equations).
Key Formula for Value of Root 2
Here’s the standard formula: \( \sqrt{2} \approx 1.414 \)
| Decimal Places | Value of Root 2 |
|---|---|
| Up to 2 decimals | 1.41 |
| Up to 4 decimals | 1.4142 |
| Up to 10 decimals | 1.4142135624 |
Cross-Disciplinary Usage
Value of root 2 is not only useful in Maths but also plays an important role in Physics for vector calculations, Computer Science for algorithms, and in daily logical reasoning. Students preparing for JEE, NEET, or Olympiad exams can find many questions where using the correct value of root 2 helps in scoring marks quickly.
Step-by-Step Illustration (Finding Value of Root 2 by Division Method)
- To find √2, group 2 as 2.00 00 00 (pair the zeros for decimals).
- Find a number such that (number) × (number) ≤ 2. Answer is 1, since 1 × 1 = 1.
- Subtract and bring down the next pair: 2 − 1 = 1, bring down 00 → 100.
- Double the divisor: 2 × 1 = 2. Place “2_” before the blank.
- Find a digit X so that (20 + X) × X ≤ 100. Here, X=4, since 24 × 4 = 96.
- Repeat the process (bring down 00, double the result, and find the next digit) to go further in decimals: Next get 14, 1.41, 1.414 etc.
Applications of Value of Root 2
- Length of the diagonal of a square with side 1 unit: Diagonal = side × √2
- In trigonometry: sin 45° = cos 45° = 1/√2
- Simplifying surds and fractions in algebra and geometry.
- Calculating shortest path, distances, and in real world measurement tasks.
Speed Trick or Vedic Shortcut
Here’s a quick shortcut: To quickly estimate values involving root 2 in competitive exam questions, remember that √2 is always about 1.414. For multiple-choice questions, you can round to 1.41 if you need only two decimal precision.
Example Trick: Whenever you see a right-angled triangle with legs of 1 unit, the hypotenuse is instantly √2 (i.e., 1.414 units), saving you time in reasoning out long steps.
Try These Yourself
- What is the diagonal of a square with side 5 cm? (Give your answer using value of root 2 up to 2 decimals.)
- Express √2 as a surd and as a decimal.
- If sin θ = 1/√2, what is θ?
- Calculate 3 × √2, rounding to two decimals.
Frequent Errors and Misunderstandings
- Using “1.42” instead of “1.41” for value of root 2 in exams.
- Thinking root 2 has a terminating or repeating decimal (it does not!).
- Assuming root 2 can be exactly written as a fraction (it can’t; it’s irrational).
Relation to Other Concepts
The idea of value of root 2 connects closely with topics such as surds, irrational numbers, and geometry (especially the Pythagorean theorem). Mastering this will help you understand more advanced ideas about square roots, trigonometric ratios, and number properties in future maths chapters.
Classroom Tip
A quick way to remember value of root 2: Think of a square with side 1. The diagonal is always √2, so “1, 1, root 2” forms a triangle. Teachers at Vedantu often ask students to visualize or draw this to make learning easier and memorable.
We explored value of root 2—from what it means, to how to calculate and use it, common mistakes, and related ideas. Keep practicing with Vedantu’s resources and videos to stay confident and accurate whenever root 2 appears in maths!
Further Learning – Related Topics
FAQs on What Is the Value of Root 2 in Maths
1. What is the value of root 2?
The value of √2 is approximately 1.41421356. It is a non-terminating and non-repeating decimal number.
- √2 cannot be written as a simple fraction.
- Its approximate value is 1.414 (rounded to three decimal places).
- It is commonly used in geometry and algebra calculations.
2. Is root 2 a rational or irrational number?
The number √2 is an irrational number. This means it cannot be expressed as a ratio of two integers.
- Its decimal expansion is non-terminating.
- Its decimal expansion is non-repeating.
- It was one of the first numbers proven to be irrational in mathematics.
3. How do you calculate the value of root 2?
The value of √2 can be calculated using the long division method or approximation methods. One simple method is:
- Start with a guess (e.g., 1.4).
- Square it: 1.4 × 1.4 = 1.96.
- Adjust the value until the square is close to 2.
4. Why is the value of root 2 important in mathematics?
The value of √2 is important because it appears frequently in geometry and algebra.
- It represents the diagonal of a square with side length 1.
- It is used in the Pythagoras theorem.
- It is common in trigonometry and coordinate geometry.
5. What is the square of root 2?
The square of √2 is 2. Mathematically, (√2)2 = 2.
- Squaring cancels the square root.
- This follows the identity (√a)2 = a.
6. What is the value of root 2 up to 3 decimal places?
The value of √2 up to three decimal places is 1.414.
- Actual value: 1.41421356...
- The fourth decimal digit is 2, so no rounding up is needed.
7. How is root 2 related to the Pythagoras theorem?
The value of √2 is the hypotenuse of a right triangle with both legs equal to 1. Using Pythagoras theorem:
- a² + b² = c²
- 1² + 1² = c²
- 2 = c²
- c = √2
8. What is the cube of root 2?
The cube of √2 is 2√2 or approximately 2.828. Calculation:
- (√2)3 = (√2 × √2 × √2)
- = 2 × √2
- ≈ 2 × 1.414 = 2.828
9. Can root 2 be written as a fraction?
No, √2 cannot be written as a fraction because it is an irrational number.
- It cannot be expressed in the form p/q.
- Its decimal expansion never ends.
- It never repeats in a pattern.
10. What is the simplified form of root 2?
The number √2 is already in its simplest radical form.
- 2 has no perfect square factors other than 1.
- It cannot be simplified further.
- Therefore, the simplest form remains √2.





















