RECTILINEAR FIGURES
Rectilinear Figure : A rectilirear figure is defined as the geometrical plane figure bounded by straight lines.
Polygon : A polygon is a plane figure bounded by three or more sides. A figure having three sides is called a triangle, four sides a rectangle, five sides a pentagon, six sides a hexagon, seven sides a heptagon and eight sides as octagon etc.
A polygon has n sides, The angle measured by two sides meeting at a vertex is called the angle of the polygon.
Types of Polygons : Polygons are of three trypes – convex, concave and regu-
lar.
Convex Polygon : If each interior angle of the polygon is less than 1800, it is
called a convex polygon.
Concave Polygon : If one interior angle is bigger than 1800, it is called concave polygon.
Regular Polygon : A polygon which has all angles and all sides equal is called a regular polygon.
Names of polygons : Polygons with different number of sides are given the following names –
No. of sides Polygon Name
- Triangle
- Quadrilateral
- Pentagon
- Hexagon
- Heptagon
- Octagon
- Nonagon
- Decagon
12 n-gon
- If three sides of a polygon are equal it is an equilateral
- If four sides of a polygon are equal it is a
Angles of a Polygon :
- If a regular polygon has n sides, each exterior angle is 360/n.
- The interior angle of a regular polygon is = 1800 – exterior
- If a convex polygon has n sides, the total of its interior angles = (2n-4) right
- The total of exterior angles of a polygon is equal to 4 right
Quadrilateral : A quadrilateral has four vertices and four sides, M, N, O, P and MN, NO, OP and PM respectively These sides do not intersect except at their end points.
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- A quadrilateral is a parallelogram, if its opposite sides and angles are equal and dingonals bisect each In this one pair of opposite sides are equal and paral- lel.
other.
- The diagonals of a rhombus bisect each other at 900.
- In a rectangle the diagonals are
- The diagonals of a square bisect each other at 900 and are equal to each
- All angles of a quadilateral on adding together come out to be 3600.
- A rhombus is a figure having all sides
- A rectangle is a figure having each angle equal to 900.
- A square is a figure which has all four sides equal and each angle is 900.
- A quadrilateral which has two pairs of equal adjacent sides but opposite sides
are unequal, the figure is called a kite.
