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We are introducing “Study Notes based Preparation” this study notes consist of very important concept of Geometry. We have analysed the SSC-CGL Mains exam, the questions asked from geometry sections are directly based on these concepts. For more such concept based notes follow us on a daily basis because from now we will provide it regularly. Every day, we’ll post different topics, Stay Tuned here.

**Polygon And Quadrilateral’s Properties**

**1.**

**Polygon: –**It is a closed plane figure bounded by three or more than three straight lines.

There are of two types of polygons.

**A polygon in which none of its interior angle is more than 180°**

__Convex:__**A polygon in which at least one interior angle is more than 180°.**

__Concave:__**Regular Polygon:**All the sides are equal and also all the interior angles are equal

Sum of Interior angles of a polygon = (n – 2) × 180

n

**→**number of sides**2. Rectangle: –**

- In a parallelogram with two adjacent angles A and B equal to each other, then the parallelogram is a rectangle or a square.
- Diagonals are equal and bisect each other, but not necessarily at right angles.
- For the given perimeter of rectangle, a square has maximum area.
- The figure farmed by joining the mid-points of the adjacent sides of rectangle is a rhombus.
- The quadrilateral formed by joining the mid points of intersections of the angle bisectors of a parallelogram is a rectangle.

**3. Rhombus: –**

- A parallelogram in which all sides are equal is called a rhombus.
- Diagonal of rhombus bisect each other at right angles, but they are not necessarily equal.
- Diagonal bisect the vertex angles.
- Sum of any two adjacent angles is 180°
- Figure formed by joining the mid-points of the adjacent sides of a rhombus is a rectangle

**4. Parallelogram: –**

- Opposite sides are parallel and equal.
- Opposite angles are equal.
- Sum of any two adjacent angles is 180°.
- Each diagonal divides a parallelogram into two congruent triangles.
- The parallelogram that inscribed in a circle is a rectangle.
- The parallelogram that circumcircle a circle is a rhombus

**5. Trapezium:-**

- A quadrilateral whose only one pair of sides is parallel and other two sides are not parallel.