In any right triangle, the square of the hypotenuse equals the sum of the squares of the other two sides: a² + b² = c².
The hypotenuse (c) is the longest side — always opposite the right angle. The other two sides (a and b) are called legs.
To find the hypotenuse: c = √(a² + b²). To find a missing leg: a = √(c² − b²).
This only works for right triangles. If there's no right angle, this formula doesn't apply.
Remember
a² + b² = c². The hypotenuse is always c — the longest side, opposite the right angle. The legs are a and b.
Real World
Builders use the 3-4-5 rule to check if a corner is truly square: measure 3 units along one wall, 4 units along the other — if the diagonal is exactly 5, the corner is 90°.
Feeling ready?
Put this concept to work with a practice workout.