Lagrangian for the double pendulum

Hello hopefully I can ask this here. In the potential energy term for the double pendulum on this Page http://ift.tt/1CR7aII Why does it appear as if the potential energy is greatest in magnitude when the pendulums are hanging straight down. I.e cosine is maximum when theta is 0, so the potential energy term appears as though it is nonzero when the pendulums are dangling straight down. Thank you in advance.