In this lesson we will be talking about a trapezoid definition and properties.
What is a trapezoid?
A trapezoid is a quadrangle shape, that has at least one pair of opposite sides parallel to each other. Note that we said “at least one pair of sides” – if the shape has two such pairs, it’s merely a rectangle. And make no mistake – every rectangle is a trapezoid. The inverse is, of course, not true.
The two sides, which are parallel, are usually called bases. Usually, we draw trapezoids the way we have shown before, which might suggest why we often differentiate between the two by saying bottom and top base. The two other non-parallel sides are called legs.
We’d like to mention a few special cases of trapezoids here.
- Rectangle
We’ve already mentioned that it is a trapezoid that has two pairs of opposite sides parallel to one another. 
- Isosceles trapezoid
A trapezoid whose legs have the same length (similarly to how we define isosceles triangles).
- Right trapezoid
A trapezoid whose one leg is perpendicular to the bases. Firstly, note how we require here only one of the legs to satisfy this condition – the other may or may not. Secondly, observe that if a leg is perpendicular to one of the bases, then it is automatically perpendicular to the other as well since the two are parallel.
With these special cases in mind, a keen eye might observe that rectangles satisfy conditions 2 and 3. Indeed, if someone didn’t know what a rectangle is, we could just say that it’s an isosceles trapezoid which is also a right trapezoid.