Hi. I'm working on a practice problem which is stumping me. Even after looking up the answer in the back of the book, I still don't understand how it was arrived at.

The question involves taking polar equation

r = 2(h*cos(t)+k*sin(t))

And coverting it to rectangular form, and verifying that it is the equation of a circle.

I keep playing around with the coord conversion equations and trig identities, but I can't seem to get it worked out. Help!