- Rectangle: Opposite sides are parallel and equal, all angles 90°. The diagonals bisect each other.
- Parallelogram: Opposite sides are parallel and equal, opposite angles are equal, diagonals bisect each other.
- Rhombus: is a parallelogram with all sides equal. Its opposite angles are equal, its diagonals bisect each other.
- Trapezium: One pair of its sides are parallel.
- Kite: Two pairs of its adjacent sides are equal, its diagonals meet at right angles, bisecting one of them.
- A line of symmetry divides a two-dimensional shape into two congruent (identical) shapes.
- A plane symmetry divides a three-dimensional shape into two congruent solid shapes.
- The number of times a shape fits its outline during a complete revolution is called the order of rotational symmetry.
|Shape||Number of Lines of Symmetry||Rotational Symmetry Order|
- Properties of circles:
- Equal chords are equidistant from the center.
- The perpendicular bisector of a chord passes through the center.
- Tangents from an external point are equal in length.
- Sum of angles at a point = 360°
- Angles on a straight line = 180°
- Sum of angles in a triangle = 180°
- For regular polygons:
- External angles = 360/n
- Sum of interior angles = 180(n – 2)
- Vertically opposite angles (X1-X1, X-X)
- Corresponding angles
- Alternate angles
- Co-interior angles
- Exterior angle = Sum of interior angles opposite the exterior angle. (d = a + b)
- The locus of points equidistant from a point is a circle.
- The locus of points equidistant between two points is a perpendicular bisector.
- The locus of points equidistant between two lines is an angle bisector.
- The locus of points equidistant (along) from a line is a parallel line.