I won't do yours for you. I'll do one exactly like it instead
and you can use it as a model to do yours by. I'll do this
one instead which uses cosine instead of sine:


Always draw this picture when converting from polar to ractangular
or from rectangular to polar::
Looking at the triangle in the picture above you can see these:
,
,
Then solve for y, x and r
,
, {r=sqrt(x^2+y^2)}}}
ALWAYS WAIT TILL LAST TO SUBSTITUTE FOR r. Substitute for x and y
first. Then simplify.




Multiply through by r


NOW, FINALLY, we substitute for r2.


<-- answer
That's it!.
Now do yours the same way, only use the sine instead.
Edwin