sstrike's answer to macdoodles's Secondary 3 A Maths Singapore question.

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sstrike
Sstrike's answer
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macdoodles
Macdoodles
11 months ago
i dont understand the second line
sstrike
Sstrike
11 months ago
2nd line is double angle identity
Refer to your text book
If you don't understand this, u cannot do all this Q