Strawbees arm servo calculations

strawrm.js

var l = 17;

var toDegrees = function( radians ) {
	return radians * ( 180 / Math.PI );
}
var toRadians = function( degrees ) {
	return degrees * ( Math.PI / 180 );
}

// Polar magnitude
var d = function( x, y ) {
	return Math.sqrt( Math.pow( x, 2 ) + Math.pow( y, 2 ) );
}

// Polar angle
var teta = function( x, y ) {
	return Math.atan2( y, x );
}

// Angle between teta and the arm
var alpha = function( x, y ) {
	var b = Math.sqrt( Math.pow( l, 2 ) - ( ( Math.pow( x, 2 ) + Math.pow( y, 2 ) ) / 4 ) );
	return Math.asin( b / l );
}

// Angle between the arm and the claw
var beta = function( x, y ) {
	return toRadians( 180 ) - ( 2 * alpha( x, y, l ) );
}

// Calculate claw and arm angles for a position x and y
var move = function( x, y ) {
	var claw = toDegrees( beta( x, y, l ) );
	var arm = toDegrees( teta( x, y ) + alpha( x, y, l ) );
	return {
		claw: claw,
		arm: arm
	}
}