Question Detail
Question
Vector A and B are said to be parallel if
Correct Answer
Option A is the correct answer.
Detailed Explanation
Two vectors are parallel when they have the same direction or opposite directions. The dot product A·B = |A||B|cosθ. For parallel vectors, θ = 0° or 180°, so cosθ = ±1. Thus |A·B| = AB. Option A correctly states A·B = AB (taking the positive case for same direction). For antiparallel vectors, A·B = -AB. The cross product A × B = 0 for parallel vectors as well, but option C is also correct depending on convention.
Hint
Parallel vectors have an angle of 0° or 180° between them. Consider both dot and cross product conditions.