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Question
The value of cos(-480°) is:
Options
`sqrt3`
`- sqrt3/2`
`1/2`
`(-1)/2`
Solution
`(-1)/2`
Explanation:
cos(-480°) = cos 480° [∵ cos(-θ) = cos θ]
= cos(360° + 120°)
= cos 120°
= cos(180° – 60°)
= -cos 60°
= `(-1)/2`
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