Tangent in Radians

In radians tangent repeats every $\pi$. At $\frac{\pi}{4}$ it is 1, at $\frac{\pi}{3}$ it is √3, at $\frac{\pi}{6}$ it is √3/3, and it is undefined at π/2 and 3π/2.

Take $\tan\left(\frac{7\pi}{4}\right)$: 2π − π/4, quadrant IV, reference π/4. Tangent is negative in IV, so $\tan\left(\frac{7\pi}{4}\right) = -\tan\left(\frac{\pi}{4}\right)$, which is −1.

Same two questions, same chip: reference angle first, then the value.