Answer:
Step-by-step explanation:
Several trig identities are involved in the proof of this. This is the order in which they are used.
- cos(2x) = cos²(x) -sin²(x)
- cos²(x) +sin²(x) = 1
- cos(x) = 1/sec(x)
<h3>Proof</h3>
Starting with the left side, we can transform it into the right side.

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Not sure but I think it’s B