4.4 Expression of a Vector as the Linear Combination of a Few Vectors
1. Polygon Law for Vectors
2. To prove that two vectors are parallel, we must express one of the vectors as a scalar multiple of the other vector.
For example, .
3. To prove that points P, Q and R are collinear, prove one of the following.
Diagram below shows a parallelogram ABCD. Point Q lies on the straight line AB and point S lies on the straight line DC. The straight line AS is extended to the point T such that AS = 2ST.
It is given that AQ : QB = 3 : 1, DS : SC = 3 : 1,
(a) Express, in terms of
(b) Show that the points Q, C and T are collinear.