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Introduction to Geometry

Here’s a quick introduction to geometry. Geometry is a branch of mathematics involved in the study of the properties of shapes and angles, and the orientation of shapes. It also deals with the relationships between points, lines, angles, shapes and its measurements.

Let’s define all these now.

point is a position or a place. A point does not have any dimensions. For example, the tip of a pencil is a point.

When we join two points, the length between them is called an interval.

introduction to geometry-interval

line is a set of points. The arrows indicate that the line goes forever in both directions.

introduction to geometry-line

If an arrow has a starting point, then it is called a ray. In other words, a line which continues in one direction forever is a ray. A beam of light from a torch is an example of a ray.

introduction to geometry-ray

When a set of three or more points lie in a straight line, we say those points are collinear. Ordering of letters is important when expressing collinear points – we write from where it starts first.

introduction to geometry-collinear

Concurrent lines are lines that pass through the same single point. Here all lines pass through A, so they are all concurrent lines.

Concurrent lines

Following this introduction to geometry, here’s some more detailed lessons:

Types of lines

Types of angles

Measuring an angle