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secondary 4 | A Maths
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genevieve
Genevieve

secondary 4 chevron_right A Maths chevron_right Singapore

very confused on how to solve these questions. Would appreciate detailed worked solution. Thanks!

Date Posted: 4 years ago
Views: 515

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Eric Nicholas K
Eric Nicholas K's answer
5997 answers (Tutor Details)
1st
Good evening Cheryl! Here are my workings for sin 3A.
genevieve
Genevieve
4 years ago
Thank you!!
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Eric Nicholas K
Eric Nicholas K's answer
5997 answers (Tutor Details)
Good evening Cheryl! Here are my workings for cos 3A.
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Eric Nicholas K
Eric Nicholas K's answer
5997 answers (Tutor Details)
Good evening Cheryl! Here are my workings for tan 3A.

Alternatively, we can express tan 3A as sin 3A divided by cos 3A, but this is a much harder approach.
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Eric Nicholas K
Eric Nicholas K's answer
5997 answers (Tutor Details)
Good evening Cheryl! Here are my workings for the remaining questions.

For Q4c, I have tried really hard to prove the final identity but I just cannot seem to obtain the final answer. I also used random numbers into the given identity and both sides of the equation do not hold. But I may be wrong somewhere in my workings.
genevieve
Genevieve
4 years ago
Thank you! I’ll try from there!!!
Boy Mow Chau
Boy Mow Chau
4 years ago
For question Q4c, there is mistake in the given "identity".

To check, can substitute some angles and see if LHS = RHS.

From substituting different angles like x=60 degrees and x=30 degrees, it looks like the mistake is the sign between the 2 terms on the LHS. It should be "+" instead of "-".