Create PHP Class function to calculate Area of Polygon

I need a programmer working on a project in which I need to calculate the area of a polygon, based on Lat/Lng points that make up the polygon. I believe what I want returned is square miles, but correct me if I'm wrong. This is probably a function that already exists out there but I could not find it easily. Easy $25 and +10 Rating for the coder if interested. Some sample coordinate values are listed below. Polygon Set 1: -118.208771,34.141361,-118.195030,34.157841,-118.175812,34.170341,-118.154518,34.210091,-118.118820,34.208389,-118.100281,34.228828,-118.129120,34.306000,-118.179932,34.425030,-118.004150,34.521259,-117.906639,34.468071,-117.673187,34.409176,-117.736359,34.233376,-117.725372,33.937805,-117.859947,33.953041,-117.877800,33.954750,-117.940971,33.965569,-117.971191,33.963860,-117.995911,33.993469,-118.045341,34.018509,-118.140099,34.033310,-118.134613,34.065739,-118.173058,34.118622,-118.208771,34.141361 Polygon Set 2: -117.970840,33.977810,-117.725708,33.938801,-117.622368,33.857868,-117.583923,33.836201,-117.533112,33.814522,-117.446587,33.783710,-117.419121,33.703770,-117.475433,33.650059,-117.512512,33.618050,-117.531731,33.564281,-117.560570,33.504749,-117.545471,33.456650,-117.584610,33.377548,-117.693947,33.452641,-117.715927,33.456219,-117.722618,33.466961,-117.826996,33.556274,-117.888786,33.589451,-117.929993,33.604889,-118.088257,33.698921,-118.097527,33.873829,-118.062851,33.917431,-117.970840,33.977810 Quick help is appreciated. I'm looking to get this done ASAP. Thanks!