What do quadrilaterals equal

There may be some confusion about this word depending on which country you're in. In India and Britain, they say trapezium ; in America, trapezium usually means a quadrilateral with no parallel sides. An isosceles trapezoid is a trapezoid whose non-parallel sides are congruent. A kite is a quadrilateral with exactly two pairs of adjacent congruent sides.

This definition excludes rhombi. Some textbooks say a kite has at least two pairs of adjacent congruent sides, so a rhombus is a special case of a kite. A scalene quadrilateral is a four-sided polygon that has no congruent sides.

Children in primary grades often find it hard to assign anything geometrical or otherwise simultaneously to two categories. Similarly, students tend to treat rectangles and parallelograms as disjoint classes, rather than seeing a rectangle as a special type of parallelograms. Another possible way to classify quadrilaterals is by examining their diagonals. This may be accessible for middle grade students who have learned about perpendicular lines and bisectors.

Tesselation: The fact that the four vertices fit snugly around a single point allows us to arrange four copies of a quadrilateral around a point. Regardless of the quadrilateral one starts with, four copies of it can be arranged to fit snugly around a single point.

Multiple copies of that foursome will tile the plane. Even if one starts with a concave quadrilateral like this , one can group four identical copies of them snugly around a point , and can tile the entire plane with multiple copies.

Cyclic quadrilaterals: For some quadrilaterals, it is possible to pass a single circle through all four of its vertices. These special cases, called cyclic quadrilaterals, include rectangles and therefore squares and isosceles trapezoids, but also other shapes that have no special name of their own. Cyclic quadrilaterals have the special property that the sum of their opposite angles is a straight angle, or degrees.

The implication works in the other direction, too: any quadrilateral whose opposite angles add up to degrees is a cyclic quadrilateral. A trapezium is a quadrilateral with one pair of parallel sides that are different lengths. A trapezoid is a quadrilateral with no parallel sides.

A trapezium has one pair of opposite sides that are parallel lines. A parallelogram is a quadrilateral with two pairs of opposite facing sides that are equal length and parallel. The opposite angles are equal.

A rhombus is a parallelogram with sides that are all equal lengths. Also opposite angles are equal angles "A" are the same, and angles "B" are the same. A trapezoid called a trapezium in the UK has a pair of opposite sides parallel. And a trapezium called a trapezoid in the UK is a quadrilateral with NO parallel sides:.

An Isosceles trapezoid, as shown above, has left and right sides of equal length that join to the base at equal angles. The only regular all sides equal and all angles equal quadrilateral is a square.

So all other quadrilaterals are irregular.