Pythagoras’ theorem states that in a right-angled triangle, the square of the length of the hypotenuse (the longest side) is equal to the sum of the squares of the lengths of the other two sides.
This can be written as:
c² = a² + b²
where c is the length of the hypotenuse, and a and b are the lengths of the other two sides.
To find the length of one of the unknown sides, we can rearrange this equation to isolate that side. For example:
- If we want to find the length of side a, we can rearrange the equation to get:
a² = c² - b²
Then we can take the square root of both sides to get:
a = √(c² - b²)
- If we want to find the length of side b, we can rearrange the equation to get:
b² = c² - a²
Then we can take the square root of both sides to get:
b = √(c² - a²)
Let’s look at an example:
Example: Find the length of the hypotenuse of a right-angled triangle with sides of length 3 and 4.
We can use Pythagoras’ theorem to find the length of the hypotenuse:
c² = a² + b²
c² = 3² + 4²
c² = 9 + 16
c² = 25
c = √25
c = 5
So the length of the hypotenuse is 5.
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