Triangle law of vector addition with expression or derivation
Law of vector addition :
The law of triangle of vector addition states:
If , the two sides of a triangle represents two given vectors in magnitude and direction in same order , then third side drawn in opposite sense represents their vector sum.
For example:
Let there be two vectors 
and 
and the angle between them is θ as shown in the picture below:
Then , To find their sum 
first of all we reposition the two vectors such that the head of vector exactly coincides with the tail of vector and then draw a vector from the tail of the vector to head of the vector
, The newly drawn vector represents the vector b sum of vectors �a� and �b� .