Pythagoras’ Theorem
Pythagoras’ Theorem is a rule used in mathematics to find the length of sides
in a right-angled triangle. A right-angled triangle is a triangle that has one
angle equal to 90°.
In a right-angled triangle, the longest side is called the hypotenuse. This is
always the side opposite the right angle. The other two sides are called the legs
(or shorter sides).
The theorem states that:
The square of the hypotenuse is equal to the sum of the squares of the
other two sides.
This means if the two shorter sides are called a and b, and the hypotenuse is c,
then the equation is:
a² + b² = c²
To use the theorem, you square the lengths of the two shorter sides, add them
together, and the result equals the square of the longest side. If you need the
length of the hypotenuse, you take the square root of the result.
Example
If a right-angled triangle has sides 3 cm and 4 cm:
Add them together:
Now find the square root:
So the hypotenuse is 5 cm.
Why it is important
Pythagoras’ Theorem is very useful in geometry, construction, engineering,
navigation, and computer graphics. It allows people to calculate distances
that cannot be measured directly.
