# How do you convert θ = (3 pi )/ 4 into cartesian form?

$\theta = \frac{3 \pi}{4} \to {P}_{1} \to \left(x , y\right) = \left(r \cos \left(\frac{3 \pi}{4}\right) , r \sin \left(\frac{3 \pi}{4}\right)\right)$
Let $\left(0 , 0\right) \text{ to point "(x,y)" be } r$
Then we have $x = r \cos \left(\theta\right) \text{ ; } y = r \sin \left(\theta\right)$
So $\theta = \frac{3 \pi}{4} \to {P}_{1} \to \left(x , y\right) = \left(r \cos \left(\frac{3 \pi}{4}\right) , r \sin \left(\frac{3 \pi}{4}\right)\right)$