4.1 Project I: Area and Perimeter of Three Given Points You are asked to develop an error free VB.Net application that can calculate the area and perimeter of three given points (see Figure 4-1). Figure 4-2 shows an example form for the application. The form, when activated, allows users to enter x1, y1, x2, y2, x3, and y3. Then the users can click the Calculate button. The area and perimeter enclosed by the three given points will be calculated and displayed at the Area and Perimeter textboxes. When users click the Clear button, the textboxes will be empty. When users click the Cancel button, the program terminates normally. x1, y1 x3, y3 X2, y2 Three Given Points Project -OX First Point Second Point yt: Third Point Area: Perimeter. Calculate . Clear Clear | Cancel The formula used to calculate the area of three given points is Area = 0.5 * (x2*y3 - y2*x3) + (xl*y2-yl*x2) + (y1*x3 - xl*y3) Or Heron's formula: S = s(sa)(s - b)( sc) Where s= (a + b + c) is the semi-perimeter, or one half of the triangle's perimeter. a b C = distance between point (x1.yl) and point (x2, y2) = distance between point (x2,y2) and point (x3, y3) = distance between point (x1.yl) and point (x3, y3) The distance between two given points can be calculated using the below formula: Introduction to Computer Programming & Numerical Methods Chapter 4 Xudong Jia & Shu Liu D = /1xl x2 +1 y1 - y21