Students can go through AP Board 9th Class Maths Notes Chapter 5 Co-Ordinate Geometry to understand and remember the concepts easily.

## AP State Board Syllabus 9th Class Maths Notes Chapter 5 Co-Ordinate Geometry

→ To locate the exact position of a point on a number line we need only a single reference.

→ To describe the exact position of a point on a Cartesian plane we need two references.

→ Rene Descartes a French mathematician developed the new branch of mathematics called Co-ordinate Geometry.

→ The two perpendicular lines taken in any direction are referred to as co-ordinate axes. © The horizontal line is called X – axis.

→ The vertical line is called Y – axis.

→ The meeting point of the axes is called the origin.

→ The distance of a point from Y – axis is called the x co-ordinate or abscissa.

→ The distance of a point from X – axis is called the y co-ordinate or ordinate.

→ The co-ordinates of origin are (0, 0).

→ The co-ordinate plane is divided into four quadrants namely Q_{1}, Q_{2}, Q_{3}, Q_{4} i.e., first, second, third and fourth quadrants respectively.

→ The signs of co-ordinates of a point are as follows.

Q_{1}: (+, +) Q_{2}: (-, +) Q_{3}: (-, -) Q_{4}: (+, -).

→ The x co-ordinate of a point on Y – axis is zero.

→ The y co-ordinate of a point on X – axis is zero.

→ Equation of X – axis is y = 0

→ Equation of Y – axis is x = 0

→ In a co-ordinate plane (x_{1}; y_{1}) ≠ (x_{2}, y_{2}) unless x_{1} = x_{2} and y_{1} = y_{2}.