cos⁻¹[cos(−680°)] equals:
cos⁻¹[cos(−680°)] equals:
- A. 40°
- B. 320°
- C. −40°
- D. 680°
Answer: A) 40°
Explanation: cos(−680°) = cos(680°) = cos(720° − 40°) = cos 40°. Since 40° ∈ [0°, 180°], cos⁻¹(cos 40°) = 40°.
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