## Geometry basic concepts Part 2, Quadrilaterals Polygons Squares

A quadrilateral is a closed shape on a plane bounded by four straight lines. To convey the concept of 'many' the word 'polygon' is used. A closed shape on a plane with many sides is a polygon. Though any number and types of polygons are possible, apart from triangles, we are generally interested in the polygons with four sides, the quadrilateral, the parallelogram, the rectangle, the rhombus and the square...