Quadrilaterals
A quadrilateral is a Having only two dimensions, usually length (or height) and width. shape with four sides.
There are six special quadrilaterals with different properties.
Square
- A square has four sides of equal length.
- It has four right angles (90掳).
- The opposite sides are parallel.
- The Line joining two non-adjacent vertices (corners) of a polygon.To divide into two equal sections, cut in half. each other at right angles.
Rectangle
- A rectangle has two pairs of equal sides.
- It has four right angles (90掳).
- The opposite sides are parallel.
- The diagonals bisect each other.
Parallelogram
- A parallelogram has two pairs of equal sides.
- It has two pairs of equal angles.
- The opposite sides are parallel.
- The diagonals bisect each other.
Rhombus
- A rhombus has four sides of equal lengths.
- It has two pairs of equal angles.
- The opposite sides are parallel.
- The diagonals bisect each other at right angles.
Trapezium
- A trapezium has one pair of parallel sides.
Kite
- A kite has two pairs of equal sides.
- It has one pair of equal angles.
- The diagonals bisect at right angles.
The sum of interior angles in a quadrilateral
This fact and the properties of quadrilaterals can be used to calculate angles.
Example
Find angle \(d\).
\(d = 360 - 100 - 70 - 30 = 160^\circ\)
Question
Find the unknown angles.
The quadrilateral is a parallelogram. Opposite angles are equal.
\(g = 50^\circ\)
Angles in a quadrilateral add up to 360掳 and opposite angles are equal.
\(f = \frac{360 - 50 - 50}{2} = 130^\circ\)