Question

cos3π=?

need a step by step explanation

plz answer properly
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Answer 1

Step-by-step explanation:

$cos \: 3 \pi \: = cos \: ( \pi \: + 2 \pi) \\ = - cos \: 2 \pi = - cos( \pi \: + \pi) \\ = - \times - cos \pi \\ = \: cos \: \pi \\ = - 1 \\ \\ \\ \{reson \} \\ \: cos \: ( \pi \: + \theta) \: = - cos \: \theta \: and \\ cos \pi \: = - 1 \}$

Answer 2

Answer:

cos3π means cos 540°

so 540-360=180°

bcoz there is max 360°

we get 180°

so value of cos 180° is -1