1.

The value of cos(-480°) is: (a) √3 (b) \(-\frac{\sqrt{3}}{2}\)(c) \(\frac{1}{2}\)(d) \(\frac{-1}{2}\)

Answer»

(d) \(\frac{-1}{2}\)

cos(-480°) = cos 480° [∵ cos(-θ) = cos θ] 

= cos(360° + 120°) 

= cos 120° 

= cos(180° – 60°)

= -cos 60° 

\(\frac{-1}{2}\)



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