Function floatsin get the sine from a given angle. The input angle may be in radians, degrees or grades.
This function name starts with a lowercase letter.
GTA/SA-MP use degrees for angles in most circumstances, for example GetPlayerFacingAngle. Therefore, it is most likely you'll want to use the 'degrees' angle mode, not radians.
Also note that angles in GTA are counterclockwise; 270° is East and 90° is West. South is still 180° and North still 0°/360°.

(Float:value, anglemode:mode = radian)
float value The angle from which to get the sine.
int anglemode The angle mode to use, depending on the value entered.

Return Values:
The sine of the value entered.

GetPosInFrontOfPlayer(playerid, Float:distance, &Float:x, &Float:y, &Float:z)
    if(GetPlayerPos(playerid, x, y, z)) // this functions returns 0 if the player is not connected
        new Float:z_angle;
        GetPlayerFacingAngle(playerid, z_angle);
        x += distance * floatsin(-z_angle, degrees); // angles in GTA go counter-clockwise, so we need to reverse the retrieved angle
        y += distance * floatcos(-z_angle, degrees);
        return 1; // return 1 on success, the actual coordinates are returned by reference
    return 0; // return 0 if the player isn't connected

Related Functions
The following functions may be useful, as they are related to this function in one way or another.
  • float: Converts an integer into a float.
  • floatstr: Converts a string to a float.
  • floatmul: Multiplies two floats with each other.
  • floatdiv: Divide one float by another one.
  • floatadd: Adds two floats together.
  • floatsub: Subtracts one float from another.
  • floatfract: Get the fractional part of a float.
  • floatround: Round a floating point number to an integer value.
  • floatcmp: Compare float values to each other, to validate the comparison.
  • floatsqroot: Calculates the square root of given value.
  • floatpower: Raises the given value to the power of the exponent.
  • floatlog: Allows you to get the logarithm of a float value.
  • floatcos: Get the cosine from a given angle.
  • floattan: Get the tangent from a given angle.
  • floatabs: Returns the absolute value of float.