Quadrilaterals

Quadrilaterals

Introduction

Quadrilaterals are very important types of polygons because they are very useful in geometry.

Quadrilaterals

Quadrilaterals are shapes that have only four sides and are polygons.

Classifying quadrilaterals

Until now we only knew that quadrilaterals are only four-sided shape, but there are many types of 4 sided shape.

• Square– has all equal sides, vertices, angles and all angles are right angles.
  
• Rectangle– has opposite equal sides and has right angles.
• parallelogram– has two parallel sides and opposite angles are equal
  
• rhombus– has all equal sides and does not have any 90° inner angles and all are not an equal angle.
  
• (US English)Trapezoid / (UK English)Trapezium–  has 1 pair of parallel sides others are not.
  
• (US English)Trapezium- has no parallel sides

Finding a missing angle of a quadrilateral.

1. First, add up all the known angles in the quadrilateral.56° + 64° + 110° = 230°
2. Remember: that the sum of the inner angle of any quadrilaterals is 360°so we have to minus the sum (230°) From 360 to find out the missing value.X°+ 56° + 64° + 110° = 360°
   
   X°+ 230° = 360°
   X° = 360° – 230°
   X°  = 130°
   so missing angle X° = 130°