could you please generate a serious of 20-minutes for 9th grade geometry

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Welcome to our introduction to geometry. We'll start with the three basic elements: points, lines, and planes. A point represents a location in space with no size or dimension. A line is a straight path that extends infinitely in both directions. And a plane is a flat surface that extends infinitely in all directions. These three undefined terms form the foundation of geometry. In geometry, a line segment is a part of a line with two endpoints. Unlike a line, a segment has a finite length. The distance between two points is the length of the line segment connecting them. On a number line, we simply find the absolute difference between the coordinates. In a coordinate plane, we use the distance formula: the square root of the sum of the squared differences of the coordinates. For example, the distance between points P and Q is approximately 5.83 units. The midpoint of a line segment is the point exactly halfway between its two endpoints. On a number line, we find the midpoint by taking the average of the two coordinates. For example, the midpoint between -3 and 5 is 1. In a coordinate plane, we apply the midpoint formula, which calculates the average of the x-coordinates and the average of the y-coordinates. For points P at (-4,-2) and Q at (2,3), the midpoint is at (-1,0.5). The midpoint formula is useful in many geometric problems, including finding centers of shapes and constructing perpendicular bisectors. An angle is formed by two rays that share a common endpoint called the vertex. The rays are the sides of the angle. We measure angles in degrees, with a full rotation being 360 degrees. To name an angle, we use three letters, with the vertex as the middle letter, like angle ABC. We can also simply refer to it as angle B when the vertex is clear. The size of an angle is measured using a protractor, which shows the degrees of rotation from one side to the other. Understanding angles is fundamental to geometry, as they help us describe the relationships between lines and shapes. Angles are classified based on their measure in degrees. An acute angle measures less than 90 degrees, like this 45-degree angle. A right angle is exactly 90 degrees and is often marked with a small square. An obtuse angle measures between 90 and 180 degrees, such as this 135-degree angle. A straight angle measures exactly 180 degrees, forming a straight line. Finally, a reflex angle measures between 180 and 360 degrees, like this 270-degree angle. Recognizing these angle types is essential for solving geometric problems and understanding the properties of shapes.