Find constraint equations (if any) that b must satisfy in order for Ax = b to be consistent. 1 2 3 -1 *d. A =| 2 -1 2 a. A = 6 -2 1 -2 1 3 1 1 1 1 1 e. A = -1 "b. A = 1 3 4 3 -1 1 1 1 1 c. A =|1 2 1 1 -1 1 f. A = 2 1 -1 1 1 -1

et △ABC be a triangle in S^2 (the two-dimensional sphere). Let the dual point C'∈S^2 of C be defined by the following three conditions:(i) d(C' , A)=π/2(ii) d(C' , B)=π/2(iii) d(C' , C)≤π/2A' and B' are defined analogously. Thus we get a dual triangle △A' B' C'. More precisely, △ABC is a non-degenerate triangle, andit follows (you may assume) that △A' B' C' is too.(question) Are there triangles △ABC in S^2 identical to their own dual △A'B'C'?   I would be very thankful if you could provide some explanation with the steps, thank you in advance.