Nelikulmioiden

Nelikulmioiden is the Finnish word for quadrilaterals. A quadrilateral is a polygon with four edges and four vertices. The four edges are line segments and the four vertices are points where the edges meet. In Euclidean geometry, a quadrilateral is a closed shape formed by four straight line segments. The sum of the interior angles of any quadrilateral is always 360 degrees.

There are many different types of quadrilaterals, classified by the properties of their sides and angles. Some common examples include squares, rectangles, rhombuses, parallelograms, trapezoids, and kites. A square has four equal sides and four right angles. A rectangle has opposite sides equal and four right angles. A rhombus has four equal sides, but its angles are not necessarily right angles. A parallelogram has opposite sides equal and parallel, and opposite angles equal. A trapezoid has at least one pair of parallel sides. A kite has two pairs of equal-length sides that are adjacent to each other.

Quadrilaterals are fundamental shapes in geometry and are found in many real-world applications, from architecture and engineering to art and design. Understanding their properties is crucial for various mathematical and practical purposes. The study of quadrilaterals often involves calculating their area, perimeter, and analyzing their symmetry.