Trigonometry Reference Angles and Triangles Give an exact value for Cos 120º.

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asked Aug 15, 2021 23.5k views

2 votes

Trigonometry
Reference Angles and Triangles
Give an exact value for Cos 120º.

Mathematics
high-school

Bivas asked

by Bivas

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2 Answers

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Explanation:

$cos \: 120 \degree \\ = cos \:( 180 \degree - 60 \degree) \\ = - cos \: 60 \degree \\ = - (1)/(2) \\ \\ \huge \purple{ \boxed{ \therefore \: cos \: 120 \degree = - (1)/(2) }} \\$

Nikes answered Aug 18, 2021

by Nikes

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4 votes

Answer:

-½

Explanation:

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

= -cos(60) = -½

JustColbs answered Aug 22, 2021

by JustColbs

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