Magnitude of the vector

The magnitude of the vector is also called the norm. It is represented by ||OA||:

To find out magnitude of this vector, we can follow the Pythagorean theorem:

OA2 = OB2 + AB2

= 42 + 32 

= 16 + 9

= 25

Hence:

OA = √25 = 5

||OA||= 5

So, if there is a vector x = (x_1,x₂,....,x_n):

||x||= x₁2 + x₂2+........+x_n2

And direction of this vector as: