3日目段階2です

em-oop/src/Rectangle.java

@@ -0,0 +1,18 @@
+
+public class Rectangle extends Shape {
+	private double width;
+	private double height;
+
+	public Rectangle(double width, double height) {
+		super("四角形");
+		this.height = height;
+		this.width = width;
+
+	}
+
+	@Override
+	public double area() {
+		return width * height;
+	}
+
+}