Answer
-1
Work Step by Step
$\frac{3\pi}{4}$ radians= $\frac{3\times180}{4}^{\circ}=135^{\circ}$
$135^{\circ}$ is in the second quadrant and tangent function is negative in the second quadrant.
As $\theta$ is in quadrant II, the reference angle is
$\theta'=
180^{\circ}-\theta=180^{\circ}-135^{\circ}=45^{\circ}$
$\tan\frac{3\pi}{4}=\tan135^{\circ}=-\tan45^{\circ}=-1$
