Math Chapter 11: Triangles, Quadrilaterals & Polygons

Sum of Interior Angles of a Polygon

(n-2) x 180 degrees

Exterior Angles of a triangle

*An exterior angle of a triangle is equal to the sum of the interior opposite angles.* *The three exterior angles of a triangle add up to 360 degrees.* Abbreviation: ext. < of ^

Sum of Exterior Angles of a Polygon

*The sum of exterior angles of any polygon is 360 degrees.* (1 int. < + 1 ext. < = 180 degrees)

Angle Sum of a Quadrilateral

*The sum of interior angles of a quadrilateral is 360 degrees.* Abbreviation: < sum of quad.

Angle Sum of a Triangle

*The sum of the interior angles of any triangle is equal to 180 degrees.* Abbreviation: < sum of ^

Regular Polygons

- all sides & angles are equal

Polygon

- closed plane figure w/ 3 or more straight line segments as its sides

Types of Triangles

1. Acute 2. Right 3. Obtuse

Classification of Triangles

1. Equilateral 2. Isosceles 3. Scalene

Types

1. Rectangle 2. Square 3. Parallelogram 4. Rhombus 5. Trapezium 6. Kite

Names

3-sided - triangle 4-sided - quadrilateral 5-sided - pentagon 6-sided - hexagon 7-sided - heptagon 8-sided - octagon 9-sided - nonagon 10-sided - decagon 11-sided - 11-gon...

Base Angles of Isosceles Triangles

Abbreviation: base <s, isos. ^

Order of Rotational Symmetry

Rotation = 360 degrees on a particular point