Example

Finding the Hypotenuse of a 3-4-5 Right Triangle

Use the Pythagorean Theorem and the geometry problem-solving strategy to find the length of the hypotenuse of a right triangle whose legs measure 33 and 44.

  1. Read: A right triangle has legs of length 33 and 44; find the hypotenuse.
  2. Identify: The length of the hypotenuse.
  3. Name: Let cc = the length of the hypotenuse. Label the figure accordingly.
  4. Translate: Write the Pythagorean Theorem and substitute the known leg lengths:

a2+b2=c2a^2 + b^2 = c^2

32+42=c23^2 + 4^2 = c^2

  1. Solve: Evaluate the squares: 9+16=c29 + 16 = c^2. Simplify: 25=c225 = c^2. Apply the square root definition: 25=c\sqrt{25} = c, so c=5c = 5.
  2. Check: Verify by substituting back: 32+42=9+16=253^2 + 4^2 = 9 + 16 = 25 and 52=255^2 = 25, so 25=2525 = 25 \checkmark
  3. Answer: The length of the hypotenuse is 55.

This example demonstrates the basic application of the Pythagorean Theorem: substitute the two known leg lengths into a2+b2=c2a^2 + b^2 = c^2, compute each square, add, and then take the square root of both sides to find the hypotenuse.

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Updated 2026-04-21

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