(Reminder: This is a 2nd week problem for school. First C++ programming class. very limited input/output knowledge at this point.) 1. The problem statement, all variables and given/known data (paraphrased) Have user input 4 ordered pairs of coordinates that go around the quadrilateral in either the CW or CCW direction. Output the area according to the standard formula: .5 * (abs( (x1y2 - x2y1) + (x2y3 - x3y2) + (x3y4 - x4y3) + (x4y1-x1y4) ) ) Then, use Heron's formula to find the area. Break the quadrilateral up into two triangles by connecting vertices 1 & 3. Find area of Triangle 1, then Triangle 2, then sum them up. Area = sqrt(s(s-a)(s-b)(s-c)) s= .5*perimeter Then, use Heron's formula again to find the area but splitting the triangle through vertices 2 & 4. 3. The attempt at a solution Okay, this is all fine and dandy and I have the program working completely, although I get an unsual error that I can't quite figure out how to fix, and it's only when the bonus question is involved. The bonus question asks "what if the quadrilateral is concave? Write reliable code that can determine whether or not the quad is concave or convex." And when I input a concave quadrilateral, such as with coordinates: (0,0)(2,0)(0,2)(1,1) I end up with the correct area being computed by the standard formula, but not by Heron's formula. This is because the 2nd triangle that is computed is outside the polygon. BASICALLY: If I have a convex quad, all of the area found (by splitting up the quad into two triangles) is inside the polygon. If i have a concave quad, one of the triangles lies outside the polygon. I can't figure out how to remedy this. I have a week to get this done so I'm in no rush.