Find the cartesian coordinate of the polar coordinate(3, 5/6) . 11) Find the polar coordinate, 0 2 and r 0 of the cartesian coordinate (1, 3). 12) Replace the polar equation r = 3 sec e^(2r sin ) with an equivalent cartesian equa- tion. 13) Evaluate integrals to find the center of mass of a thin plate covering the region bounded y = x and x-axis over the interval [0, 4].