# 6.4 Equations of Straight Lines (Part 1)

1. Gradient of the line joining (x1, yl) and (x2, y2) is:

2. Gradient of the line with knowing x–intercept and y–intercept
is:

3. The gradient of the straight line joining P and Q is equal to the
tangent of angle θ, where θ is the angle made by the straight line
PQ and the positive direction of the x-axis.

(B) Collinear points
The gradient of a straight line is always constant i.e. the gradient of AB is equal to the gradient of BC.

Example 1:
The gradient of the line passing through point (k, 1 – k) and point
(–3k, –3) is 5.  Find the value of k.

Solution:

Example 2:
Based on the diagram below, find the gradient of the line.

Solution: