# RD Sharma Solutions for Class 9 Maths Chapter 7: Introduction to Euclid's Geometry

In 300 BCE, Greek Mathematician Euclid came out with some new solid figures and studied the plane. That was later named Euclidean Geometry. Euclidean geometry mainly deals with planes and solid geometry, basic geometric properties such as properties related to points and lines. These geometric object's propositions and coordinates were not used to specify the location of the objects.

In this chapter, we will learn about some topics which are the very fundamentals for learning geometry. A line Segment is a part of a line that is joined by 2 points. Intersecting lines are two lines that join in a common point, and Parallel lines are two lines in which if we take the distance between 2 points in each line, they will always be the same, and these lines will never intersect each other. Concurrent Lines are sets of more than 2 lines which intersect on a single point, and Collinear points are 2 or more points if they lie on the same line.

Some notations and terminology that are very important in Euclidean geometry are naming the points and figures. Points are generally named in capital letters similar to as in lines, triangles, or any other closed figures. The figures are named by listing a sufficient number of points to pick them out whenever a certain part of the figures needs addressing, such as points A, B, C, D in a square ABCD.

Euclidean geometry involved two major components: Angle and Distance. Euclid only uses the right angle as his basic unit as the angle scale is absolute. On the other hand, the distance scale is relative because the distances are expressed by arbitrarily picking a line segment with a certain non-zero length as the unit.