polygons

UNIT: POLYGONS & QUADRILATERALS

Arts & Crafts

Definition

Polygon: A plane shape (two-dimensional) with straight sides.

Classification

• Regular or irregular: If all angles are equal and all sides are equal, then it is regular, otherwise it is irregular.

Classification

• Concave or Convex: In a convex polygon, no internal angles can be more than 180°.If any internal angle is greater than 180° then the polygon is concave. (Think: concave has a "cave" in it)

Quadrilateral

• Quadrilateral just means "four sides" (quad means four, lateral means side). A Quadrilateral has four straight sides, it is 2-dimensional (a flat shape), and closed (the lines join up).

Vertex: Capital lettersSides: Small letters Diagonal: segment that join 2 non-consecutive vertex. The addition of the 4 angles is 360°

Classification

• Parallelogram: A 4-sided flat shape with straight sides where opposite sides are parallel.

-Square: 4 equal sides. Angles 90°. Equal and perpendicular diagonals. -Rectangle: opposite sides are equal. Angles 90°. Equal diagonals. -Rhombus: 4 equal sides. Non equal but perpendicular diagonals. Opposite angles are equal.

Classification

• Trapezium: It is a 4-sided flat shape with straight sides that has a pair of opposite sides parallel.

Classification

• Trapezoid It is a 4-sided flat shape with straight sides and no parallel sides.

Constructing polygons

Square given the diagonal

• -Draw the diagonal
• -Draw the perpendicular bisector
• -Finally, draw the circumference radius AO

Constructing polygons

Rhombus given 2 diagonals Rectangle given one side and the diagonal

Regular polygons inscribed in a circle

The circumcircle (circunferencia circunscrita) of a regular polygon is the circle that passes through every vertex of the polygon. Every vertex is at the same distance to the center. Once the circumference is draw, you only have to divide it in equal parts to construct triangles, hexagons, squares, octagons and pentagons.

UNIT: POLYGONS & QUADRILATERALS

Arts & Crafts