Question

2 (cos² 20 + cos²140 + cos²100)
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Answer 1

Answer:

3/2

3

4

none of these

Answer :

B

Solution :

2(cos220∘+cos2140∘+cos2100∘)

=3+cos40∘+cos280∘+cos200∘

=3+2cos120∘cos160∘+cos200∘

=3−cos160∘+cos200∘

=3−cos(360∘−200∘)+cos200∘

=3−cos200∘+cos200∘

= 3

Step-by-step explanation:

Answer 2

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