Answer:
It would've been more difficult to solve and doing it as shown in EX:2 it's a way easier method to use and remember.
The last name I am pretty sure of it.
Answer:
<h3><u /></h3>
<u>Trigonometric identities</u>
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Therefore, using the <u>identities</u>, the given expression can be <em>simplified</em> as follows:

It is B glad I could help!