How do I convert r^2 sin(2 theta) = 8 into Cartesian form?

Question

zepdrix · Answer

$$\Large\bf\sf r^2 \color{royalblue}{\sin(2 \theta)}\quad=\quad 8$$We want to mess with this blue part first.
Do you remember your Sine Double Angle Identity? :)

zepdrix · Answer

$\Large\bf \color{#008353}{\text{Welcome to OpenStudy! :)}}$

anonymous · Answer

Is that sin^2+cos^2=1? D:

zepdrix · Answer

Nooo you silly billy.
That's the Square Identity for Sine and Cosine.
The Double Angle Formula for Sine is,$$\Large\bf\sf \sin(2\theta)=2\sin \theta \cos \theta$$Look familiar?

zepdrix · Answer

$$\Large\bf\sf r^2 \cdot \color{royalblue}{2\sin \theta \cos \theta}\quad=\quad 8$$

anonymous · Answer

and where do I go from there? Do I divide 8 by 2sin(theta)cos(theta) and convert r^2 into x^2+y^2? 
Sorry so confused!!

anonymous · Answer

$$
r^22\sin\theta\cos\theta = 2(r\sin\theta)(r\cos\theta)
$$