The tangent of angle of the line with the x – axis in anticlockwise direction is called slope of the line.
It is denoted by m.
Slope of the line AB,
Example 1: Find the slope of a line which makes an angle of with the positive direction of y – axis. 
Solution 1: Angle with x – axis in positive direction =

SLOPE OF A LINE IN TWO POINT FORM
Let A and B be two points on the line whose coordinates are and respectively.
Draw
AM = PQ = OQ – OP = x_{2} – x_{1}
BM = BQ – QM = BQ – AP =y_{2} – y_{1}
Example 2: Find the slope of a line passing through the points A(5, – 2) and B(–3, 4). 
Solution 2: 
NOTE:
1. Slope of a line parallel to x – axis is zero.
The angle of line AB with x – axis zero is: .
2. Slope of a line parallel to y – axis is .
The angle of line PQ with axis is .
The range of slope is .