C#で座標(Point)が矩形(Rectangle)の範囲内か調べる方法

Rectangle.Contains()メソッドで範囲内の座標か調べることが出来ます。
サンプルコード

using System.Drawing;

var rect = new Rectangle(30,50,100,100);
var points = new List<Point>{ new Point(0,0), new Point(50,50), new Point(100,100)};

foreach(var pt in points)
{
    Console.WriteLine("Point({0},{1})はRectangle({2},{3},{4},{5})の範囲内？{6}",
        pt.X, pt.Y,
        rect.X, rect.Y, rect.Width, rect.Height,
        rect.Contains(pt)
    );
}

結果

Point(0,0)はRectangle(30,50,100,100)の範囲内？False
Point(50,50)はRectangle(30,50,100,100)の範囲内？True
Point(100,100)はRectangle(30,50,100,100)の範囲内？True