Pythagorean theorem, step by step

Every answer on these sheets is a whole number, and that is on purpose.

The question
43? cm

Right triangle, 3 and 4

34?
  1. The hypotenuse is the side OPPOSITE the right angle — never one of the two that make the corner. It is also always the longest, so you can check yourself twice.
  2. Here the hypotenuse is the missing one, so the two given sides are both legs: 3 and 4.
  3. Square the two you have: 3² = 9 and 4² = 16.
  4. The two squares ADD to the square on the hypotenuse: 9 + 16 = 25.
  5. That is the square, not the side. Take the square root: √25 = 5 cm.

How it works.

  1. 01

    The hypotenuse is the side OPPOSITE the right angle — never one of the two that make the corner. It is also always the longest, so you can check yourself twice.

  2. 02

    Here the hypotenuse is the missing one, so the two given sides are both legs: 3 and 4.

  3. 03

    Square the two you have: 3² = 9 and 4² = 16.

  4. 04

    The two squares ADD to the square on the hypotenuse: 9 + 16 = 25.

  5. 05

    That is the square, not the side. Take the square root: √25 = 5 cm.