Kahwai's answer to MM's Secondary 4 A Maths Singapore question.

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Kahwai
Kahwai's answer
232 answers (A Helpful Person)
For part 2

0 0<2X<2Pi()

Then

Differentiate y
You get something with cot(2X)

Equate both
Left with sine(2x) and cosine (2x)

Then using (a2+b2)^0.5 sin(theta + alpha) formula or sine square plus cosine square =1

You will get the answers