Pythagorean Theorem
Hypotenuse from two sides.
Hypotenuse from two sides.
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The Pythagorean theorem is arguably the most-used result in all of geometry: in any right triangle, the square on the hypotenuse equals the sum of the squares on the two legs. Builders, navigators, and screen manufacturers all rely on it daily.
Enter the two legs (the sides forming the right angle). The calculator squares them, sums, and takes the square root for the hypotenuse — and also returns the triangle's area and perimeter as a bonus.
a and b are the legs, c the hypotenuse (always the longest side). Area = a×b ÷ 2; perimeter = a + b + c.
Legs of 3 and 4: c = √(9 + 16) = √25 = 5 — the famous 3-4-5 triangle, used since antiquity to lay out perfect right angles with a knotted rope.
Rearrange: a = √(c² − b²). A 10-meter ladder (hypotenuse) with its base 6 m from the wall reaches √(100 − 36) = 8 m up.
No — it's exclusive to right triangles. For others use the law of cosines, c² = a² + b² − 2ab·cos(C), which reduces to Pythagoras exactly when C = 90°.
Whole-number solutions like (3,4,5), (5,12,13), (8,15,17) — and every multiple of them, such as (6,8,10). Handy for quick mental checks and construction layouts.
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