Cosine of Supplementary Angle/Examples/Theta minus 180
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Example of Cosine of Supplementary Angle
- $\map \cos {\theta - 180 \degrees} = -\cos \theta$
Proof
| \(\ds \map \cos {\theta - 180 \degrees}\) | \(=\) | \(\ds \map \cos {180 \degrees - \theta}\) | Cosine Function is Even | |||||||||||
| \(\ds \) | \(=\) | \(\ds -\csc \theta\) | Cosine of Supplementary Angle |
$\blacksquare$
Sources
- 1953: L. Harwood Clarke: A Note Book in Pure Mathematics ... (previous) ... (next): $\text V$. Trigonometry: Exercise $\text {XXXI}$: $9.$