Sec 1 Quadrilaterals and Polygons

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www.ApexEducators.com 1 Name : _________________________ Date: _________________________ Secondary 1 Mathematics – Quadrilaterals and Polygons 1. Types of Polygons Number of sides Name and Drawing Number of sides Name and Drawing 3 sides 7 sides 4 sides 8 sides 5 sides 9 sides 6 sides 10 sides Note: A regular polygon has all sides of the same length and all angles are equal. The sum of interior angles of an n-sided polygon = ("−2)×180° The size of each interior angle of a regular n-sided polygon = ("#$)×'()°" The sum of exterior angles of a n-sided polygon = 360° The size of each exterior angle of a regular n-sided polygon = +,)°" Note: Interior angle + Exterior angle = 180° (supplementary angles)

www.ApexEducators.com 2 Example: Triangle The sum of interior angles of a triangle = (3−2)×180° = 1×180° = 180° The size of each interior angle of an equilateral triangle = (+#$)×'()°+ = 60° The size of each exterior angle of an equilateral triangle = +,)°+ or 180°−60° = 120° The sum of the exterior angle of an equilateral triangle = 360° Example: Rectangle The sum of interior angles of a rectangle = (4−2)×180° = 2×180° = 360° The size of each interior angle of a rectangle = (-#$)×'()°- = 90° The size of each exterior angle of a rectangle = +,)°- or 180°−90° = 90° The sum of the exterior angle of a rectangle = 360°

www.ApexEducators.com 3 2. Angle Properties of Quadrilaterals Name Description Figure Trapezium • One pair of parallel opposite sides Parallelogram • Two pairs of parallel opposite sides. • Opposite sides are equal in length • Opposite angles are equal • Diagonals bisect one another Rhombus • Two pairs of parallel opposite sides. • Four equal sides • Opposite angles are equal. • Diagonals bisect one another at 90° • Diagonals bisect the interior angles. Rectangle • Two pairs of parallel opposite sides. • Opposite sides are equal in length. • Diagonals are equal in length. • Diagonals bisect one another.

www.ApexEducators.com 4 Square • Two pairs of parallel