Hello friends! Today we talk about a very famous math rule called Pythagoras Theorem. This theorem is super old, like thousands of years old, and it was made by a man named Pythagoras from Greece. He was a smart guy who loved math. This theorem is used in triangles, but not any triangle, only special ones called right-angled triangles. If you study math in school or need to solve problems about triangles, this theorem is like your best friend! Letâs learn it in simple way.
Definition
Okay, so what is Pythagoras Theorem? the definition is:
In a right-angled triangle, the square of the length of the hypotenuse is equal to the sum of the squares of the lengths of the other two sides.

A right-angled triangle is a triangle where one angle is 90 degrees (like a corner of a square). This theorem tells us how the sides of this triangle are connected. The sides have special names:
- Hypotenuse: This is the longest side, opposite to the 90-degree angle.
- Base and Perpendicular: The other two sides that make the right angle.
The theorem says: If you take the length of the two shorter sides, square them, and add them, it will equal the square of the longest side (hypotenuse). Simple?
Formula
Now, letâs see the formula. Itâs very easy to remember:
a² + b² = c²
Here:
- a and b are the lengths of the two shorter sides (base and perpendicular).
- c is the length of the hypotenuse (longest side).
For example, if you know the length of two sides, you can find the third side by using this formula. Just put the numbers in, and youâre done!
Examples
Letâs do some examples to make it super clear. These are like real problems you solve in school.
Example 1: Finding the Hypotenuse
Suppose a right-angled triangle has:
- Base (a) = 3 cm
- Perpendicular (b) = 4 cm
- Hypotenuse (c) = ?
Using Pythagoras Theorem:
a² + b² = c²
3² + 4² = c²
9 + 16 = c²
25 = c²
So, c = â25 = 5 cm
The hypotenuse is 5 cm. Easy, right?
Example 2: Finding a Side
Now, letâs say you know:
- Hypotenuse (c) = 10 cm
- Base (a) = 6 cm
- Perpendicular (b) = ?
Using the formula:
a² + b² = c²
6² + b² = 10²
36 + b² = 100
b² = 100 – 36
b² = 64
So, b = â64 = 8 cm
The perpendicular is 8 cm. See, itâs like a game!
Conclusion
So, friends, Pythagoras Theorem is a super useful rule for right-angled triangles. It helps us find the length of a side if we know the other two sides. The formula a² + b² = c² is simple and works every time. Whether youâre doing homework, building something, or even playing games with math, this theorem is always there to help. So, next time you see a right-angled triangle, just remember Pythagoras and his cool rule! Keep practicing, and youâll become a pro in no time.