# Lia's Math – Home page

## Polygons and Circle – Definitions, Perimeter and Area formulas

Posted in Math Theory by Lia on 04/02/2013

## Polygon

### triangle

A triangle with unequal sides and therefore unequal angles.

### triangle

#### In this case the angle A is larger than 90˚. ### triangle

#### A triangle that has no angle larger than 90˚. ### Isosceles triangle

#### In this case AB = AC and angle B is equal with angle C. ### Equilateral triangle

#### In this case AB = BC =CA and angle A = angle B = angle C. ### Right triangle

#### In this case angle A = 90˚ and therefore AC is perpendicular on AB and reverse (AB is perpendicular on AC). ### (general shape) ### Parallelogram

#### In this case AB = CD; AC = BD; angle A = angle D and angle B = angle C. ### Rhombus

#### A parallelogram that has all sides equal. ### Rectangle

#### A parallelogram that has all angles equal with 90°. ### Square

#### A rectangle that has all sides equal. ### Scalene trapezoid

#### A trapezoid that has no equal  sides or angles. ### Right trapezoid

#### In this case angle A = angle C = 90°. ### Isosceles trapezoid

#### In this case AC = BD and angle A= angle B and angle C = angle D. ### Polygon (general shape)

#### There are 5 triangles inside this heptagon (a polygon with 7 sides).  One triangle has the sum of its angle therefore the polygon will have 5 times the sum of the trianle’s angles (  ## Circle

### Circle ### Circle sector

#### A circle sector  is the portion of a circle in between two radii. ### Circle segment

#### A circle segment is the portion of a circle in between a chord and the arc that has same end points as the chord. Tagged with: ,