Adding function to math object

1

i have this functions and i want to add to math object but i get this errors

[FONT=times new roman][SIZE=1]FUNCTION[/SIZE][/FONT]
[COLOR=red]
[COLOR=blue]
/*******************************************

  •        Distance function             *

/
[/COLOR]
Math.prototype.distance = function (x1,y1,x2,y2) {
var dx=x2-x1;
var dy=y2-y1;
return Math.sqrt(dxdx+dydy);
};
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/**

  •       Radians to Degrees             *

/
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Math.prototype.radToDeg = function (angle) {
return angle(180/Math.PI);
};
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/

  •  SINE FUNCTION = HEIGHT (_y)        *

*****************************************/
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Math.prototype.sinD = function (angle) {
return Math.sin(angle(Math.PI/180));
};[/COLOR]

[FONT=arial][SIZE=1]ERROR[/SIZE][/FONT]
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Error Scene=Scene 1, layer=Layer 1, frame=1:Line 2: There is no method with the name ‘radToDeg’.
trace(Math.radToDeg(Math.PI));
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Total ActionScript Errors: 1 Reported Errors: 1