If cos⁻¹x + cos⁻¹y = 2π, then the value of xy is:
If cos⁻¹x + cos⁻¹y = 2π, then the value of xy is:
- A. 1
- B. -1
- C. 0
- D. 2
Answer: A) 1
Explanation: The maximum value of cos⁻¹(x) is π. For the sum to be 2π, both must be π. Thus x = -1 and y = -1. Their product xy = 1.
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