Rectangle

From Wikipedia, the free encyclopedia

In geometry, a rectangle is defined as a quadrilateral where all four of its angles are right angles.

From this definition, it follows that a rectangle has two pairs of parallel sides of equal length; that is, a rectangle is a parallelogram. A square is a special kind of rectangle where all four sides have equal length; that is, a square is both a rectangle and a rhombus. A rectangle that is not a square is colloquially known as an oblong.

Of the two opposite pairs of sides in a rectangle, the length of the longer side is called the length of the rectangle, and the length of the shorter side is called the width. The area of a rectangle is the product of its length and its width; in symbols, A = lw. For example, the area of a rectangle with a length of 5 and a width of 4 would be 20, because .

Both a square and a rectangle are quadrilaterals and have four parallel sides.

In calculus, the Riemann integral can be thought of as a limit of sums of the areas of arbitrarily thin rectangles.

[edit] External links

• Eric W. Weisstein, Rectangle at MathWorld.
• Definition and properties of a rectangle With interactive animation
• Area of a rectangle with interactive animation