Eric Nicholas K's answer to Cheryl's Secondary 3 A Maths Singapore question.
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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)
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)
Date Posted:
2 years ago
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