3-4-5 triangle
Hypotenuse c: 5.00
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Pythagorean theorem calculator
Pythagorean theorem: a² + b² = c², with a worked example.
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5-12-13 triangle
Hypotenuse c: 13.00
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Cathete b: 12.00
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Frequently asked questions
What is the Pythagorean theorem?
In a right triangle, a² + b² = c². Here a and b are the legs and c is the hypotenuse.
What is the hypotenuse?
The hypotenuse is the longest side of the right triangle and is opposite the right angle.
How do I calculate a missing catheter?
With b = √(c² − a²). To do this, the hypotenuse c must be larger than the known leg a.
Does the theorem apply to every triangle?
No, only for right triangles. Without a right angle you need other formulas.
An example?
With a = 3 and b = 4, c = √(9 + 16) = √25 = 5. This is the well-known 3-4-5 triangle.
Are decimal numbers also allowed?
Yes, you can also enter values like 3.5 or 12.8.
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Sources and notes
Rule status and context
- Formula
- a² + b² = c²; c = √(a² + b²); b = √(c² − a²)