# What is the Cartesian form of ( -12 , (-3pi)/4 ) ?

$x = r \cos \theta = - 12 \cos \left(\frac{- 3 \pi}{4}\right) = 8.49$
$y = r \sin \theta = - 12 \sin \left(\frac{- 3 \pi}{4}\right) = 8.49$