Answer
$\dfrac{3\pi}{4} \ Radians $
Work Step by Step
In order to convert the result from degrees to radians, we multiply by $\dfrac{π}{180^{\circ}}$.
Therefore
$135^{\circ}=(135) \times \dfrac{\pi}{180}\text{radians} \\=\dfrac{3\pi}{4} \ Radians $
