Pythagorean Theorem Formula
c is the side opposite the right angle. The identity is equivalent to the distance formula in the coordinate plane.
Variables
- a, b — Legs
- c — Hypotenuse
When to use it
Right triangles, distance between points, and magnitude of a 2D vector.
Worked example
a=3, b=4
- c=5
Answer: 5
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Example problems
Common mistakes
Assigning c to a leg
The hypotenuse is longest. If a number is smaller than a leg, it cannot be c.
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Frequently asked questions
Is the converse true?
Yes. If a² + b² = c², the triangle is right-angled at C.