Polar Integration Question

Hi all,

The question -

Calculate

R is the region inside the circle

My attempt (converting to polar) -

Assuming we can find a quarter of the circle, than multiply by 4 for the total area...

Here I'm stuck and quite frankly it's looking a lot more complicated than I imagine it should, can someone please point out the error in my working?

On the off chance I am correct so far, can I treat those sections as radians? I don't believe I can as that wasn't the context they were used originally, so what would I do?

Thanks for your time folks.