Question

The resultant of two vectors of magnitudes 3 units and 4 units is 1 unit. What is the value of their dot product ?

• A. -12 units
• B. -7 units
• C. -1 unit
• D. zero

Answer 1

The correct option is A -12 units

They are in opposite directions as $4-3=1$
Hence dot product will be product of their magnitudes multiplied by cos$\theta$ which is -1 in this case. This gives dot product $=-4\times 3=-12$