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Vanliga Fel vid Pythagoras Sats & Hur Du Rättar Dem

Got an answer that looks way too big, smaller than a triangle leg, or gave an imaginary negative root error? Check your arithmetic below or return to our verified Pythagoras equation solver to inspect every step automatically.

Diagnosis updated: Forgot to take square root. You calculated c² = a² + b² = 25, which is the area of the hypotenuse square, not the length c. Take the square root of 25 as the final step.

Interactive Pythagorean Error Debugger

Enter your triangle values and the result you calculated to identify exactly which step went wrong.

Enter numeric values to diagnose Pythagorean calculation mistakes.
Test Common Errors:
Diagnosis: Forgot to take square root

You calculated c² = a² + b² = 25, which is the area of the hypotenuse square, not the length c. Take the square root of 25 as the final step.

Corrected Steps
  1. 1. Identify Pythagorean hypotenuse formula: c = √(a² + b²)
  2. 2. Square and add both legs: c = √(3² + 4²) = √(9 + 16) = √25
  3. 3. Take the positive square root: c = 5

4 Vanligaste Misstagen: Rätt mot Fel

Side-by-side diagnostic breakdown of why homework errors happen and the exact algebra fix.

1. Forgetting to Take the Square Root

Wrong Calculation
c = a² + b² → 3² + 4² = 25
Correct Approach
c = √(a² + b²) → √(3² + 4²) = √25 = 5

Why it happens: Summing the squares computes c² (area of the square on the hypotenuse), not the side length c itself.

2. Adding Instead of Subtracting for a Missing Leg

Wrong Calculation
a = √(c² + b²) → √(5² + 3²) = √34 ≈ 5.83
Correct Approach
a = √(c² - b²) → √(5² - 3²) = √16 = 4

Why it happens: Students leave the equation in standard hypotenuse-addition order instead of isolating a² = c² - b², producing a leg longer than the hypotenuse c.

3. Subtracting in Reverse (c ≤ b) or Getting Negative Radicands

Wrong Calculation
a = √(b² - c²) when b = 4, c = 5 → √(16 - 25) = √(-9)
Correct Approach
Always verify c > b, then compute √(c² - b²)

Why it happens: Subtracting c² from leg² or assigning the shorter number as hypotenuse c yields a zero or negative value under the square root.

4. Hypotenuse Assigned to the Wrong Side or Mixed Units

Wrong Calculation
a = 12 in, b = 2 ft → 12² + 2² (mixed inches and feet)
Correct Approach
a = 12 in, b = 24 in → √(12² + 24²) = 12√5 in

Why it happens: Placing the hypotenuse (always opposite the 90° right angle) into a leg slot or mixing feet/inches or cm/m invalidates the triangle geometry.

Frequently Asked Troubleshooting Questions

In a valid Euclidean right triangle, the hypotenuse c is strictly opposite the largest angle (90°) and must always be the longest side. If your computed hypotenuse is smaller than one of the legs, you either forgot to take the square root of a decimal < 1 cleanly, subtracted a² - b² instead of adding a² + b², or mistakenly entered the hypotenuse into one of the leg inputs.

Exact Radical Form Hypotenuse SolverMain Pythagoras Solver →