Trigonometry: Trigonometric functions
Computing function values
If you know the values of the cosine and sine of special angles between #0# and \(\tfrac{1}{2}\!\pi\), then you can calculate the values of special angles between \(\tfrac{1}{2}\!\pi\) and \(2\pi\) by using mirror symmetry.
Given \(\cos(\tfrac{1}{3}\!\pi)=\tfrac{1}{2 }\), what is \(\cos(\tfrac{2}{3}\!\pi)\)?
Given \(\cos(\tfrac{1}{3}\!\pi)=\tfrac{1}{2 }\), what is \(\cos(\tfrac{2}{3}\!\pi)\)?
| \(\cos(\tfrac{2}{3}\!\pi)={}\) |
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