Coefficients:

Cd/m = 0.002
g = 9.81
v_0 = 1500

-------------------------------
In the air:

x_t = y_t = 200

theta_0 = 0.786058489654712 rad
          0.784398069889900 ?
---------------------------
On ground:

x_t = 100
y_t = 500

theta_0 = 1.373889633562333 rad
or
theta_0 = 1.570798178459540 rad ?

-------------------------------
In the air:

x_t = 1500
y_t = 100

theta_0 = 0.141200599087991 rad
or
theta_0 = 0.844333510781423 rad ?

--------------------------------
In the air

x_t = 1000
y_t = 1000

theta_0 = 0.830245756357908 rad

--------------------------------