 # Understanding Quadrilaterals

## All the diagonals of a convex polygon lie entirely inside the polygon. In a concave polygon some diagonals will lie outside the polygon. Each angle of a convex polygon is less than 180°. At least one angle of a concave polygon is more than 180°. All the sides and angles of a regular polygon are equal. In an irregular polygon, all the sides and angles are not equal. Sum of interior angles of a polygon with n sides = (n – 2) x 180° Each interior angle (regular polygon) = [(n – 2) × 180°] / n. The sum of all the exterior angles of a convex polygon of n sides is always equal to 360°. The sum of all the angles of a quadrilateral is 360°. Opposite sides of a parallelogram are equal. Opposite angles of a parallelogram are equal. Diagonals of a parallelogram bisect each other. Adjacent angles of a parallelogram are supplementary. All sides of a rhombus are of equal length. The diagonals of a rhombus are perpendicular bisectors of each other. Opposite angles of a rhombus are of equal measure. Opposite sides of a rhombus are parallel to each other. The opposite sides of a rectangle are parallel to each other and are equal in length. All angles of a rectangle are right angles. The diagonals of a rectangle are equal in length and bisect each other. A square is a rhombus in which each interior angle is equal to 90° and both the diagonals are equal. A square is a rectangle in which all sides are equal and diagonals intersect at right angle. The diagonals of a square are perpendicular bisectors of each other. Keywords: Plane surface, Plane curve, Trapezium, Kite.

To Access the full content, Please Purchase