The velocity is decomposed in x and y directions, and the operational differential equations are given respectively:

X direction: x''(t)=-mrx'(t)

In the y direction, the gravity is greater: y''(t)=-mg-mry'(t)

Substitution of initial conditions: x(0)=0, y(0)=0, x'(0)=vx, y'(0)=vy (V0 is also decomposed into vx and vy).

Solvable:

x(t)=vx( 1-e^(-mrt))/(mr)

y(t)=(g-mgrt+r*vy-(g+r*vy)*e^(-mrt))/(mr？ )

This is the parametric equation of trajectory. Given time t, coordinates can be obtained. Of course, t must be between 0 and landing.

Ruling: m= 1, g=9.8, r=0.03, vx=500, vy=400.

You can draw pictures and call it ballistics.

In practice, the relationship between drag coefficient and speed is more complicated and it is much more difficult to solve.