Sum of Two Vectors: Magnitude & Scalar Product

[jdief]

Homework Statement

If the magnitude of the sum of two vectors is less than the magnitude of either vector, then:
-the vectors must be parallel and in the same direction
-the scalar product of the vectors must be negative
-none of these
-the scalar product of the vectors must be positive
-the vectors must be parallel and in opposite directions

Homework Equations

V1+V2=V3
A(dot)B=ABcos(θ)

The Attempt at a Solution

I know the answer is that the scalar product of the vectors must be negative, but I don't get why.

 

[SammyS]

Homework Statement

If the magnitude of the sum of two vectors is less than the magnitude of either vector, then:
-the vectors must be parallel and in the same direction
-the scalar product of the vectors must be negative
-none of these
-the scalar product of the vectors must be positive
-the vectors must be parallel and in opposite directions

Homework Equations

V1+V2=V3
A(dot)B=ABcos(θ)

The Attempt at a Solution

I know the answer is that the scalar product of the vectors must be negative, but I don't get why.

Hello jdief. Welcome to PF !

What have you tried?