Mind Map
Coordinate Geometry of Class 9
The linear equation
ax + by + c1 = 0 can also be written as y = mx + c.
The graph of the form y = c is a line parallel to x-axis.
The graph of the form x = c is a line parallel to y-axis.
Two perpendicular lines XOX′ and YOY′ intersecting at a point O are called coordinate axes.
The coordinates of origin are (0, 0). The abscissa of every point on y-axis is zero.
The ordinate of every point on x-axis is zero.
For y = mx + c.
If we change c to c1, c2, c3 ………
If c is increased the graph moves up.
If c is decreased the graph moves down.
These lines XOX′ and YOY′ divides the region into four quadrants. XOY, YOX′, X′OY′, Y′OX are 1st, 2nd, 3rd and 4th quadrants respectively.
The sign of x and y in 1st coordinate are (+, +), in 2nd coordinate are (–, +) in 3rd coordinate are (–, –) and in 4th coordinate are (+, –).
The perpendicular distances of a point from coordinate axis are called coordinate of that point P(x, y).
The perpendicular distance of a point from y-axis is called abscissa (x).
The perpendicular distance of a point from x-axis is called ordinate (y).
On increasing the value of m for m> 0 in y = mx. The graph, rotates anticlockwise but remain in 1st and 3rd quadrant on decreasing the value of m for m< 0 in y = mx, the graph rotates clockwise and remain in II and IV quadrants.
