# Trigonometry Identities

### Negative angles:

- (
**Still Positive!)**

Reason: is in the **“C” quadrant** so **Cosine is still positive**.

### Supplementary angles:

- (
**Still positive!**)

Reason: is in the **“S” quadrant** so **Sine is still positive**.

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Reblogged this on Singapore Maths Tuition and commented:

I realize that many students from top IP schools don’t know these formula! (Not entirely their fault since the teachers don’t teach/emphasize it.)

Nevertheless, they are often tested in the harder A Math Trigonometry questions, it is a must to know if you are aiming for A1.

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