Properties of an Isosceles Trapezoid

An Isosceles trapezoid is a quadrilateral, therefore it has four straight lines.

An isosceles trapezoid has legs of equal length and one pair of parallel sides.

The parallel sides are called bases and the non-parallel sides are called legs.

An isosceles trapezoid also has base angles congruent. The term congruent means equal.

The height, which is an altitude, is a perpendicular line that runs from base to base.

The angles at the top of the base and the bottom of the bases are congruent.

Adjacent base angles of an Isosceles trapezoid are supplementary which means they add to 180 degrees.

In order to find the perimeter add the length of all sides.

The area is equal to the average of the two bases times the height.

a+b/2 x height

The median is a line half-way between the bases.

The length is the average of the two base lengths

Median = a + b/2

The diagonals of an isosceles trapezoid have the same length and divide into the same proportions.

MooMooMath and Science YouTube

What is a trapezoid?

LCM and GCF 77 and 91

Leave a Comment angles sides isosceles trapezoid, Area of a trapezoid, quadrilaterals, trapezoid

The Quadrilateral Family Story

Let me introduce you to the quadrilateral friends and family. 

A four-sided family that lives on Geometry road.
There are three main members of the family, kite, trapezoid, and parallelogram. 

Like any family group they look and act similarly, but are also very different. 

Kite had two consecutive pairs of sides the same, but her opposite sides were not equal. Her diagonals were as well unequal. She enjoyed putting on fabric and flying high in the sky.

Trapezoid had one pair of parallel sides and nice supplementary legs. Although trapezoid was friendly, family and friends could never figure out accurately what defined her. 

Parallelogram, with her two units of parallel sides, was extremely popular and was the first family member to marry. She eventually had two little shapes, rhombus, and rectangle.

Rectangle had his mother's form, several parallel sides, and several 90-degree angles. 

Rhombus was an excellent son with equivalent sides, two pairs of parallel sides, and equal opposite angles. Mom was proud of the stunning shapes of her two kids.

One afternoon rectangle and rhombus told their mother they wanted a new family pet shape. Rectangle desired a three-sided family pet, rhombus wished a five-sided pet shape. 

Mom said, “I really know what to do, I will be right back." When she returned she had the brand new pet form, “meet square” she said. "He is the best, two parallel sides, equal sides, and four 90 degree angles." Rhombus and Rectangle agreed he was the perfect pet polygon and adored their new family pet shape.

Let’s connect

MooMooMath

Types Quadrilaterals

Properties Rhombus

Angles 1 side straight line

What is a trapezoid?

3 comments geometry, moomoomath and science, parllelogram, quad family, quadrilateral family, quadrilateral story, quadrilaterals, rhombus, square

Difference Convex and Concave Quadrilaterals

In this video, you will learn the difference between a convex quadrilateral and a concave quadrilateral.

A quadrilateral is a four-sided polygon, but what is a convex Quadrilateral?

Quadrilaterals come in different shapes and sizes, and many common shapes we encounter daily are quadrilaterals.

A few examples include,

square

rectangle

parallelogram 

rhombus

kite

Quadrilaterals can be further divided by the interior angle measurements.

A convex quadrilateral has interior angles 180 degrees or less. 

A concave quadrilateral has an interior angle measure greater than 180 degrees. Most common quadrilaterals are convex, and they do not have any interior angle measure greater than 180 degrees. 

CONVEX QUADRILATERALS

What is a concave quadrilateral?

A concave quadrilateral has a reflex interior angle measure. In other words, one interior angle measure is greater than 180 degrees.

CONCAVE QUADRILATERALS

A dart is one example of a concave quadrilateral.

A helpful method for memorizing the difference between these two types of quadrilaterals is to think of a cave for a concave quadrilateral. The reflex angle creates a cavity of a cave, which has an angle measure greater than 180 degrees.

Related Links

Isosceles Trapezoid

Quadrilaterals

1 comment 180 degree angle, concave quadrilateral, convex quadrilateral, four sided, geometric shapes, geometry, moomoomath, polygon, quadrilaterals, reflex angle