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Pythagorean Theorem Calculator and Solver

Math Geometry • Basic Shapes and Properties

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Solve right-triangle sides using \(a^2 + b^2 = c^2\) — compute the hypotenuse, find a missing leg, or verify whether three sides form a right triangle.

Tip: In “Solve” modes, the computed side is locked (you can’t type into it). In “Verify”, all three sides are editable.

Mode
Inputs
Leg \(a\)

One of the two perpendicular sides.

Leg \(b\)

The other perpendicular side.

Hypotenuse \(c\)

The longest side (opposite the right angle).

Ready
Enter values and click Solve.
Visualization

Drag to pan • Wheel/trackpad to zoom • “Reset view” restores framing.

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Frequently Asked Questions

How do I use the Pythagorean theorem to find the hypotenuse?

For a right triangle with legs a and b, the hypotenuse is c = sqrt(a^2 + b^2). Enter a and b to compute c.

How do I find a missing leg using the Pythagorean theorem?

Rearrange a^2 + b^2 = c^2 to isolate the missing leg: a = sqrt(c^2 - b^2) or b = sqrt(c^2 - a^2). The hypotenuse c must be larger than either leg.

How can I check if three side lengths form a right triangle?

Treat the largest side as c and test whether a^2 + b^2 equals c^2. Small differences can occur due to rounding, so calculators often use a tolerance.

What is the hypotenuse in a right triangle?

The hypotenuse is the longest side and it lies opposite the 90-degree angle. In the Pythagorean theorem it is labeled c.

Why does the calculator require c to be greater than a or b when solving for a leg?

Because c is the hypotenuse, it must be the longest side of a right triangle. If c is not larger than the known leg, c^2 - leg^2 becomes zero or negative and no valid real leg length exists.