line segment has two end points.A ray has only one end point (its vertex).A line has no end points on either side. This chapter throws light on topics such as related angles, pair of lines. The chapter deals with different types of angles and lines. The types of angles discussed in this chapter are as follows:Pairs of Angles ConditionTwo complementary angles Measures add up to 90°Two supplementary angles Measures add up to 180°Two adjacent angles Have a common vertex and a common arm but no common interiorLinear pair Adjacent and supplementaryA linear pair is a pair of adjacent angles whose non-common sides are opposite rays.All the types are discussed in detail and are supplemented with examples and short questions. Under the topic pair of lines, various sub-sections are discussed namely:Intersecting linesTransversal Angles made by a transversalWhen two lines intersect (LOOKING like the letter X) we have two pairs of opposite angles. They are CALLED vertically opposite angles. They are EQUAL in measure.A transversal is a line that intersects two or more lines at distinct points.Six angles discussed in this section:1. Interior angles2. Exterior angles3. Pairs of Corresponding angles4. Pairs of ALTERNATE interior angles5. Pairs of Alternate exterior angles6. Pairs of interior angles on the same side of the transversal