Maple can also handle this problem when we don't specify values of all
the parameters. Suppose you wanted to study how the distance the
projectile travels varies with the firing angle. To tell Maple that
the value of 
can vary, just execute the following command.
> theta := 'theta';
Now, if you go back and resubmit the solve command, you will get a different result.
> t_hit := solve(y(t) = 0,t);
Now the time that it takes for the projectile to hit the ground
depends on the angle . To visualize how the distance depends
on , we can plot it with the following command.
> plot(x(t_hit[2]),theta = 0..Pi/2);