[MindYourDecisions] presents a Babylonian tablet dating back to around 1800 BC that shows that the hypotenuse of a unit square is the square root of two or 1.41421. How did they know that?

What it means is that in a right triangle (where one angle equals 90°), the sum of the squares of two sides equals the square of the hypotenuse (the longest side).

Simply brace the lipped side of the speed square against the edge of your board, pencil a line up the hypotenuse of the speed square, and voilà! You have a perfect 45-degree angle for easy corners.

Pythagoras’ theorem is a statement that is true for all right-angled triangles.It states that the area of the square on the hypotenuse close hypotenuseThe longest side of a right-angled triangle ...

which states that the sum of the squares of a right triangle's two shorter sides are equal to the square of the triangle's ...