Åk 6–9
3.3 Quadrangles
A quadrangle is a polygon which has four corners and four sides.

A square is a quadrangle with right angles and equal sides.  The area is calculated by multiplies the sides by each other.

Area = s · s = s2

Perimeter = s + s + s + s = 4s

A rectangle is a quadrangle with right angles.  All squares are rectangles.  The area is calculated by multiplying the length times the height.

Area = a · b

Perimeter = a + a + b + b =
2a + 2b = 2(a + b)

A rhomb is a quadrangle where with equal sides.

Area = a · h

Perimeter = a + a + a + a = 4a

The area of a rhomb can even be calculated by multiplying together the diagonals and dividing the product by 2.

Area =
d1 · d2

A parallelogram is a quadrangle where the opposite sides are parallel.

Area = b · h

Perimeter = a + b + a + b =
2a + 2b = 2(a + b)

A trapezoid is a quadrangle with two parallel sides.

Area = h(a + b)

The diagonal is the line which connects two opposite corners in a quadrilateral.  In squares and rectangles, both diagonals are equal to each other, but not in rhombuses and parallelograms.