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Geometry

Pythagorean Calculator

Find the longest side of a right triangle.

Let’s calculate.

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Hypotenuse (c)
—units
Rounded to up to 2 decimal places.

Measurement units

Changing the input unit also selects its matching result unit. Choose another result unit to convert the answer. Input numbers stay unchanged.

SI prefixes and selected international / customary units. Coverage: SI and selected current customary units. Historical units are excluded.

See what you’re calculating

abc
c = √(a² + b²)

Enter the two perpendicular sides a and b. The answer c is the longest side.

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THE IDEA, SIMPLY

How it works

For a right triangle, square the two shorter sides, add them together and take the square root.

FORMULA

c = √(a² + b²)

A worked example

For sides 3 and 4: c = √(9 + 16) = 5.

Formula & detailed explanation

a and b must be positive and expressed in the same unit. c is the hypotenuse, opposite the right angle. This relationship applies only to right triangles.

Calculations use decimal arithmetic with 40 significant digits internally. Choose 0–8 decimal places for the displayed result. Trailing zeros are omitted. Rounding affects only the displayed and copied result; very small values may round to zero. Accepted inputs have up to 100 characters and magnitudes from 10⁻¹⁰⁰ to 10¹⁰⁰, plus zero.

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