How to Find a Shorter Side Using Pythagoras' Theorem
Finding a Shorter Side Using Pythagoras' Theorem
The length of the side is is found using the formula:
In the formula, a and b are the lengths of the shorter sides and c is the length of the hypotenuse. The image below shows what we mean:
How to Find the Hypotenuse Using Pythagoras' Theorem
What is the unknown length, a, of the right triangle below?
Find the lengths of the sides from the right triangle.
In our example, the known side lengths are b = 6 and h = 10.
Substitute b = 6 and c = 10 into the formula.
a = √(102 − 62) = √((10 × 10) − (6 × 6))
c = √(100 − 36) = √64
a = 8
The length of the shorter side, a, is 8.
A Real Example of How to Find a Shorter Side Using Pythagoras' Theorem
In the example above, we have used the formula a = √(c2 − b2) to find the length of the side, a.
This is just a rearrangement of the more memorable formula, a2 + b2 = c2 (see Note).
If you find this simpler formula easier to remember, use it!
Substitute in the lengths you know (replace the letters b and c with numbers) and then rearrange to find the side, a.
The slider below gives a real example of how to find a shorter side using Pythagoras' theorem.Open the slider in a new tab
There are two shorter sides, a and b. It does not really matter which of the shorter sides is labelled a and which is labelled b.
The formula b = √(c2 − a2) can also be used.
The slider below gives another real example of how to find a shorter side using Pythagoras' theoremOpen the slider in a new tab