What is the tangent of 45 degrees on the unit circle?
The tangent of an angle in the unit circle is given by $ \tan(\theta) = \frac{\sin(\theta)}{\cos(\theta)} $.
For $ \theta = 45^{\circ} $ or $ \theta = \frac{\pi}{4} $ rad:
$$ \sin(45^{\circ}) = \frac{\sqrt{2}}{2} $$
$$ \cos(45^{\circ}) = \frac{\sqrt{2}}{2} $$
Therefore,
$$ \tan(45^{\circ}) = \frac{\sin(45^{\circ})}{\cos(45^{\circ})} = \frac{\frac{\sqrt{2}}{2}}{\frac{\sqrt{2}}{2}} = 1 $$