This question is driving me crazy! Please help relieve my sanity. I'm sure it easy and I have just completely lost the plot.
One approach of many:
Polar coordinates: and .
Therefore:
.... (1)
.... (2)
Results that will be needed:
From (1):
.... (A)
.... (B)
From (2):
.... (C)
.... (D)
Then:
.... (E)
.... (F)
where the results (A) - (D) are to be substituted into (E) and (F).
Then substitute (E) - (F) into , do a little bit of re-arranging and then the job's done.