There are two possible answers - that depend on the context.
The second definition is sometimes used by airlines for cabin luggage. The outside shape of the case matters, not how big it is inside.
A diagonal is a line so the area of any diagonal must be zero.
The diagonal of a circle is its diameter
A diagonal cannot be a side of a rectangle, and a side cannot be a diagonal.
Use Pythagoras: Diagonal² = √(2 × sidelength²) → diagonal = side_length × √2 → diagonal = 12 × √2 ≈ 17.0 units
Kitty-corner is another term for diagonal. A right triangle's hypotenuse is on a diagonal. On a keypad, the five is on a diagonal from the nine.
diagonal
A diagonal is a line so the area of any diagonal must be zero.
The diagonal of a circle is its diameter
A diagonal cannot be a side of a rectangle, and a side cannot be a diagonal.
Use Pythagoras: Diagonal² = √(2 × sidelength²) → diagonal = side_length × √2 → diagonal = 12 × √2 ≈ 17.0 units
Kitty-corner is another term for diagonal. A right triangle's hypotenuse is on a diagonal. On a keypad, the five is on a diagonal from the nine.
The address of the Diagonal Printing Museum is: 101 East 1St Street, Diagonal, IA 50845
Using Pythagoras: diagonal² = side² + side² = 2 × side² → side² = diagonal² ÷ 2 area = side² = diagonal² ÷ 2 → diagonal² = 2 × area → diagonal = √(2 × area) = √(2 × 36) = 6√2 ≈ 8.49
The diagonals are perpendicular to one another. The shorter diagonal is bisected by the longer diagonal. The kite is symmetrical about the longer diagonal. The longer diagonal bisects the angles at each end of the diagonal.
Use Pythagoras: Diagonal² = √(2 × sidelength²) → diagonal = side_length × √2 → diagonal = 10 cm × √2 ≈ 14.1 cm
Use Pythagoras: Diagonal² = √(2 × sidelength²) → diagonal = side_length × √2 → diagonal = 5.1 cm × √2 ≈ 7.2 cm
diagonal