1. The problem statement, all variables and given/known data Find the value of the 2-form dxdy+3dxdz on the oriented triangle with (0,0,0) (1,2,3) (1,4,0) in that order. 2. Relevant equations 3. The attempt at a solution I have tried various subtraction of these coordinates and applying them to the formula but the answer is in the back of the book and I fail to see how one could get that answer. The book does not give one example of how to calculate with 2-forms there is but a brief description and then 4 problems. This is a problem from Edward's, 'Advanced Calculus: A Differential Forms Approach' The answer is a negative rational number. I also fail to see how I derive a rational number from this.