Question

cosθ+cos3θ=cos2θ+cos4θ​

Answer 1

Answer:

We have cosθ + cos7θ + cos3θ + cos5θ = 0 ⇒ 2cos4θ cos3θ + 2cos4θ cosθ = 0. ⇒ cos4θ ( cos3θ + cosθ ) = 0 cos4θ (2 cos2θ cosθ) = 0.

Step-by-step explanation:

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Answer 2

Answer:

we have cos +cos70+cos 30+cos 50=0-

2 cos 40 cos 30 +20 cost 40 cos =0=cos 40 (cos 30+cos 0)=0 cos 40 (2 cos 20 cos)=0

Step-by-step explanation:

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