Step 1: How to use this calculator?

{'step': 1, 'description': 'Square both legs: 5.5² = 30.and 12.3² = 151.29'}

Step 2: How to use this calculator?

{'step': 2, 'description': 'Add squares: 30.25 + 151.29 = 181.54'}

Adding legs directly instead of squaring first (5.5 + 12.3 ≠ hypotenuse)

Forgetting to take square root after adding the squares

Calculateur du Théorème de Pythagore

Last updated: 2026-08-24

Calculateur du Théorème de Pythagore — Calculez l'hypoténuse d'un triangle rectangle à partir des deux cathètes.

Inputs

Result

Enter values and press Calculate

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How to use it

{'step': 1, 'description': 'Square both legs: 5.5² = 30.and 12.3² = 151.29'}
{'step': 2, 'description': 'Add squares: 30.25 + 151.29 = 181.54'}
{'step': 3, 'description': 'Take square root: √181.54 = 13.4737 (hypotenuse)'}
{'step': 4, 'description': 'surface = (5.5 × 12.3) ÷ 2 = 33.825; Perimeter = 5.5 + 12.3 + 13.4737 = 31.2737'}

Common mistakes

⚠️ Adding legs directly instead of squaring first (5.5 + 12.3 ≠ hypotenuse)
⚠️ Forgetting to take square root after adding the squares
⚠️ Using this formule for non-right triangles where it doesn't apply

Worked example

Find the hypotenuse of a right triangle with legs 5.5m and 12.3m for roof rafter calculetion

The hipotenusa ({hipotenusa}) is the longest side opposite the right angle; area_triangulo ({area_triangulo}) is half the product of legs; périmètre ({périmètre}) is Total boundary length.

Input guide

Field	Typical range
cateto_a	Construction: 0.5-50m; Surveying: 1-1000m; General: any positive value
cateto_b	Same as cateto_a; both must be positive non-zero values