Shikaku is a Japanese word that means quadrilateral or four-sided shape. It refers to any polygon that has exactly four sides and four angles. Examples of shikaku include squares, rectangles, rhombuses, and trapezoids. All of these shapes share the common property of having four sides, but they can have different angles and side lengths.
All quadrilaterals, regardless of their specific shape, share certain fundamental properties. Every quadrilateral has exactly four sides, four vertices or corners, and four interior angles. Most importantly, the sum of all interior angles in any quadrilateral always equals 360 degrees. This is a universal property that applies to squares, rectangles, rhombuses, trapezoids, and any other four-sided polygon.
There are several special types of quadrilaterals, each with unique properties. A square has all sides equal and all angles are 90 degrees. A rectangle has opposite sides equal and all angles are 90 degrees. A rhombus has all sides equal with opposite angles being equal. A parallelogram has opposite sides that are both parallel and equal in length. These special quadrilaterals are commonly used in mathematics, architecture, and everyday life.
Each type of quadrilateral has its own area formula. For a square, the area is side length squared. For a rectangle, it's length times width. A rhombus area is calculated using half the product of its diagonals. For a parallelogram, we multiply the base by the height. A trapezoid's area is the average of the parallel sides multiplied by the height. These formulas are essential for solving geometry problems and real-world applications.
Quadrilaterals are fundamental shapes that appear everywhere in our daily lives. In architecture, we see them in buildings, windows, doors, and floor plans. Technology uses quadrilaterals in computer screens, tablets, and circuit board designs. Sports fields like soccer pitches and basketball courts are rectangular. Even simple everyday objects like books, tables, and picture frames are quadrilateral shapes. Understanding quadrilaterals helps us appreciate the geometric foundation of our built environment and solve practical problems in design, construction, and engineering.