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secondary 3 | A Maths
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Cheryl
Cheryl

secondary 3 chevron_right A Maths chevron_right Singapore

pls help

Date Posted: 2 months ago
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Eric Nicholas K
Eric Nicholas K's answer
5807 answers (Tutor Details)
1st
We use a series of double-angle formulae to do this question. Note that the angle pair does not have to be specifically 2x and x; as long as one angle is twice of another, the formula remains valid.

In other words,
sin 2x = 2 sin x cos x
sin 4x = 2 sin 2x cos x

(because 2x is twice of x while 4x is twice of 2x)