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secondary 3 | A Maths
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Ong Jia Zhi
Ong Jia Zhi

secondary 3 chevron_right A Maths chevron_right Singapore

How to do 9b? Need R-formula?

Date Posted: 2 months ago
Views: 20
Eric Nicholas K
Eric Nicholas K
2 months ago
One way is double angle AND R-formula.
The other way is to convert "1" into sin2x + cos2x.

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Eric Nicholas K
Eric Nicholas K's answer
1286 answers (Tutor Details)
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You can use either double-angle formula followed by R-formula to get the answer or my method below.

EDIT (for the one on top): Change '-3 cos x' to '-3 cos 2x'.