Omar was trying to determine cos (-2pi/3). he remembered the ratios of the 30 - 60 - 90 right triangle

Question

Mathematics

Yadiel Whitney

19 September, 16:13

Omar was trying to determine cos (-2pi/3). he remembered the ratios of the 30 - 60 - 90 right triangle

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Answers (1)

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Alina Owens · Answer 1

-2/3π=-120°

Therefore cos (-3/2π) is equal to:

cos (-120) = cos 120=-cos (180-120)

but using the right angle triangle:

cos 60=0.5

hence

the value for our question will be:

cos (-3/2π) = - 0.5