I have a question for a problem in my homework. I was given the following differential equation

r(1) = 2

When i solved the equation I get

My question is how do I go for solving for c? I know to just plug in 2 for r and 1 for theta. Is this problem in polar form? I have not covered polar form in any of my classes so that is where I think I am lost. any help would be appreciated.