# 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.

LCM and GCF 77 and 91