Let u and v be two vectors given in component form by
u = <u1 , v1> and v = <u2 , v2>
The dot product of the two vectors u and v above is defined by
u.v = <u1 , v1> . <u2 , v2> = u1*u2 + v1*v2
and it is a scalar quantity (rather than a vector).
How to use the calculator
1 - Enter the components of the two vectors as real numbers and press "Dot*". If by mistake characters other than numbers are entered, the calculator does not display any answer. The answer is a scalar.
More on vectors.