CHAPTER 6 LINES AND ANGLES
Line segment: A line segment is a line with two end points.
Ray: A part of the line with one end point is called a ray.
Collinear points: If three or more points lie on the same line, they are called collinear points
Non-collinear points: If three or more points do not lie on the same line they are said to be non-collinear.
Angle: An angle is formed when two rays originate from the same end point.
Arms: The arms of an angle are the rays that make the angle.
Vertex: The end point at which the rays making the angle meet is called the vertex.
TYPES OF ANGLE:
Acute angle: An angle measuring between 0o and 90o is an acute angle.
Right angle: An angle equal to 90o is called a right angle.
Obtuse angle: An angle measuring greater than 90obut less than 180o is called an obtuse angle.
Reflex angle: An angle measuring greater than 1800 but less than 3600 is called a reflex angle.
Complementary angles: Two angles whose sum is 90o are called complementary angles.
Supplementary angles: Two angles whose sum is 180o are called supplementary angles.
AXIOMS AND THEOREMS
Linear pair axioms:
Axiom 1: If a ray stands on a line, then the sum of two adjacent angles so formed is 180o.
Axiom 2: If the sum of two adjacent angles is 180o, then the non-common arms of the angles form a line.
Corresponding angles axiom:
Axiom 3: If a transversal intersects two parallel lines, then each pair of corresponding angles is equal.
Axiom 4: If a transversal intersects two lines such that a pair of corresponding angles is equal, then the two lines are parallel to each other.