Question 1
Consider "Since all triangles are plane figures, all non-plane figures are non-triangles." This inference, drawn by contraposition, is
◦ valid
◦ not valid
◦ valid by limitation
Question 2
Consider "Since all triangles are plane figures, some plane figures are triangles." This inference, drawn by conversion, is
◦ valid
◦ not valid
◦ valid by limitation