How to get Screen size of a windows phone 8 device?

Question

I was searching for how can i get the Actual screen size of a windows phone 8 device , i've found this method but it work only with Devices With GDR3 update

Answer 1

UPDATED : i've found this method

private void getScreenInfo() 
{
    double dpix = -1.01;
    double screensize = -1.01;
    double dpiy = -1.01;
    Size res;
    try {
        dpix = (double)DeviceExtendedProperties.GetValue("RawDpiX");
        dpiy = (double)DeviceExtendedProperties.GetValue("RawDpiY");
        res = (Size)DeviceExtendedProperties.GetValue("PhysicalScreenResolution");
        screensize = Math.Sqrt(Math.Pow(res.Width / dpix, 2) + Math.Pow(res.Height / dpiy, 2));
    }
    catch (Exception e) {
    }
}