Solutions of Straight Line & Angle from Mathematics Class - 9

This topic discusses the meaning of collinear points. Three or more points that lie on the same line are called collinear points. It also comprises examples to help us gain a better understanding of the concept.

In this topic, the students will learn about lines and angles. For example, when two rays (part of a straight line) intersect each other in the same plane, they form an angle. It is further explained in-depth in the text.

This topic elaborates on adjacent, complementary and supplementary angles. Complementary angles are two angles that sum to 90 degrees, supplementary angles sum to 180 degrees, and adjacent angles have common vertex and side.

This topic explains the angle made by two intersecting lines. It explains how vertical angles are always congruent, which means that they are equal, and mentions that adjacent angles are angles that come out of the same vertex.

This topic discusses the properties of vertically opposite angles. A pair of vertically opposite angles are always equal to each other. It mentions that vertical angles and adjacent angles make supplementary angles, i.e., they add up to 180 degrees.

The topic sheds line on the concept of parallel lines and transversal lines. With the help of examples, both types of lines are explained. Furthermore, the angles formed when a transversal line intersects parallel lines are also discussed.

This topic elaborates on the various properties of corresponding angles and alternate angles. It also explains the difference between them with the aid of figures.

The topic discusses the theorem based on the exterior angles of a triangle. It highlights that the exterior angle and sum of interior angles are equal. There are examples given to support the theorem.