Dreptunghiuri

A rectangle is a quadrilateral with four right angles. It is a type of parallelogram, meaning that opposite sides are parallel and equal in length. The diagonals of a rectangle are equal in length and bisect each other. Rectangles are commonly used in geometry and in various fields such as architecture, engineering, and design due to their simplicity and symmetry.

The area of a rectangle is calculated by multiplying its length by its width. The perimeter of a rectangle is the sum of all its sides, which can be calculated by adding twice the length and twice the width. Rectangles can be classified into different types based on their properties. A square is a special type of rectangle where all four sides are equal in length. An oblong is a rectangle with a length that is greater than its width, while a rhomboid is a rectangle with a width that is greater than its length.

Rectangles are also used in trigonometry to define the trigonometric functions sine and cosine. In a right-angled triangle, the sine of an angle is the ratio of the length of the opposite side to the length of the hypotenuse, and the cosine of an angle is the ratio of the length of the adjacent side to the length of the hypotenuse. These functions are fundamental in many areas of mathematics and science.