Answer
$\dfrac{ -20 \pi}{9} \ rad $
Work Step by Step
In order to convert the value from degrees to radians, we multiply by $\dfrac{π}{180^{\circ}}$.
Therefore
$-400^{\circ}=(-400) \times \dfrac{\pi}{180}\text{radians} \\=\dfrac{ -20 \pi}{9} \ rad $
