If a and b are unit vectors and θ is the angle between them, what is the maximum value of |a + b| + |a − b|?
If a and b are unit vectors and θ is the angle between them, what is the maximum value of |a + b| + |a − b|?
- A. 2
- B. 2√2
- C. 4
- D. 2√3
Answer: B) 2√2
Explanation: |a+b| = 2cos(θ/2) and |a−b| = 2sin(θ/2). Let f(θ) = 2cos(θ/2) + 2sin(θ/2). The maximum value of Acosx + Bsinx is √(A² + B²). So max value = √(2² + 2²) = √8 = 2√2.
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