Why is the scalar product negative when the sum of two vectors has smaller magnitude?

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jdief
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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.
 
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jdief said:

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?