Parallel Lines Theorem Small 320×55 Medium 640×109 Large 1024×175 Download Tiff Original 2400×410 | (58.9 KB) Description Illustration used to prove that "If two straight lines are parallel to a third straight line, they are parallel to each other." Keywords geometry, line, parallel lines, proof, prove, theorem, theorems Galleries Geometric Theorems and Proofs Source: C. A. Hart & Daniel D. Feldman Plane And Solid Geometry (New York: American Book Company, 1911) 66
