Question

(1) cos theta + cos 3theta = cos 2theta + cos 4theta
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Answer 1

Answer:

hope it will help you.......

Step-by-step explanation:

cos theta + cos 3theta = cos 2theta + cos 4theta

cos theta(1+cos 2theta)= cos2theta(1+cos2theta)

cos theta= cos 2theta

=) cos 2theta/cos theta= 1

cos theta= 1