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The Pythagorean Theorem

For a right triangle with legs a and b and hypotenuse c, a²+b²=c².

How it works

For a right triangle with legs a and b and hypotenuse c, a²+b²=c². Name the quantities before calculating, keep each transformation logically equivalent, and check the result against the original conditions.

Worked example

Find the hypotenuse when the legs are 5 and 12.

  1. Square the legs: 25 and 144.
  2. Add: 25+144=169.
  3. Take the positive square root: √169=13.

The hypotenuse is 13.

Try it now

These questions come from the same validated skill generator used by the game.

Common mistakes

  • Using a remembered formula without identifying what each symbol represents.
  • Changing a value or condition during an intermediate step.
  • Skipping the final substitution, estimate, or logical check.

Challenge

Determine whether side lengths 8, 15 and 17 form a right triangle.

Questions learners ask

What is the key idea in the pythagorean theorem?

For a right triangle with legs a and b and hypotenuse c, a²+b²=c².

How should I check an answer?

Substitute it into the original conditions, check units and signs, and decide whether its size is reasonable.