Labelling line segments
A line segment is a line with finite length which is shown by end points. The end points are labelled with capital letters.
For example, this line segment
Lines in a plane
A plane is described as a flat two dimensional surface. There are two types of straight lines in a plane. The first one would be an intersection straight line (see below)
The second one is a parallel, which are two lines which never meet and are equal distance (equidistant) apart.
Vertically opposite angles
In lines where there is an intersection, two two pairs of vertically opposite angles are created.
In perpendicular lines, two lines intersect at right angles.
The distance from a point to a line
The shortest distance from the point to the line is always the perpendicular distance.
Angles are formed when two lines meet at a point which is a measure of rotation from one of the line segments to the other. Angle labels are made using lower case letters or Greek letters and in mathematics, a positive rotation is anticlockwise.
Types of angle
Types of angles are labelled in the below diagram.
Angles on a straight line and at a point
The rules for angles on a straight line and at a point is as follows:
Complementary and supplementary angles
Complementary and supplementary angles are described as follows:
Angles made with parallel lines
When two parallel lines are crossed by a straight line, eight angles are formed. The crossed line is also called a traversal.
Corresponding, alternate and interior angles
The definition of corresponding, alternate and interior angles are as follows: