Use calculus to find the area of a triangle with given vertices (0,0) (3,1) (1,2) The answer is 5/2, I just don\'t know how to get it. You must use the fundamental theorem of calculus. Thank you in advance. All those who try will get a 5 star rating :)! Solution Area= |Ax(By-Cy)+Bx(Cy-Ay)+Cx(By-Ay)|/2 =0+3+2/2 =5/2.