Answer: cos(theta) = 1/2.
- A cos(theta) = 1/2
- B cos(theta) = 1
- C cos(theta) = 0
- D cos(theta) = sqrt(2)
Correct answer: A. cos(theta) = 1/2
Explanation: a.b = 0+1+0 = 1. |a| = sqrt(2), |b| = sqrt(2). cos(theta) = 1/(sqrt(2)*sqrt(2)) = 1/2. theta = 60 degrees.
Triangle law of vector addition: placing vector b at the head of vector a, the diagonal from the start to the final head gives the resultant a + b.
Concept context
Vectors, dot product, cross product, and geometric applications