Backward driving

#include <a_samp>
main() {}
forward MObject();
public OnPlayerCommandText(playerid,cmdtext[])
{
    SetTimer("MObject",500,1);
	return 1;
}
public MObject() {
	new veh = GetPlayerVehicleID(0);

 	new str[64];

 	new Float:x, Float:y, Float:z, Float:a1;
 	GetVehicleVelocity(veh, x, y, z);

 	GetVehicleZAngle(veh, a1);

 	new Float:c = floatsqroot(x * x + y * y);
 	new Float:a = asin(y / c);

 	if (x < 0) a = 90 - a;
 	else a = 270 + a;

 	if (a1 >= 180.0) a1 -= 180.0;
 	else a1 += 180.0;

	if (floatabs(a1-a) < 10.0 && c > 1.0) format(str, 64, "You drive backward!");

 	format(str, 64, "%s Angle 1: %.2f, Angle 2: %.2f", str, a, a1);
 	SendClientMessage(0, 0xFFFFFFFF, str);
}