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secondary 3 | A Maths
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Nicole
Nicole

secondary 3 chevron_right A Maths chevron_right Singapore

Please help! Thank you.

Date Posted: 3 years ago
Views: 257
sstrike
Sstrike
3 years ago
(a)
sin2x = 2sinx•cosx
2•sin2x - 3•cosx = 0
4•sinx•cosx - 3•cosx = 0
cosx•(4•sinx - 3) = 0
⇨ cosx = 0
⇨ sinx = ¾

x₁ = 90°
x₂ = 270°
x₃ = 48.59°
x₄ = 131.41°
sstrike
Sstrike
3 years ago
(b)
cos2θ = 1 - 2•sin²θ

sinθ = a
2•(1 - 2a²) + 3a -2 = 0

4a² -3a = 0

a•(4a-3) = 0

⇨ a = sinθ = 0

⇨a = sinθ = ¾

θ₁ = 0°
θ₂ = 180°
θ₃ = 360°
θ₄ = 48.59°
θ₅ = 131.41°
sstrike
Sstrike
3 years ago
similar
https://ask.manytutors.com/questions/118889
sstrike
Sstrike
3 years ago
similar
https://ask.manytutors.com/questions/118889

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Cheng
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Pooh pooh bear
Pooh Pooh Bear
3 years ago
Why change 2sin2x to 4sin cos x