[Pramāṇa](https://indike.org/pramana/) › [Studies](https://indike.org/pramana/ins) › [Science, technology and education](https://indike.org/pramana/ins.science) › [Indian Mathematics](https://indike.org/pramana/ins.science.kaye-1915) › c7.46 # Indian Mathematics c7.46 Indian Mathematics c7.46 - **Language:** English ### [c7.46](https://indike.org/pramana/ins.science.kaye-1915.c7.46) This figure is sometimes termed "Brahmagupta's trapezium." From the triangles (3, 4, 5) and (5, 12, 13) a commentator obtains the quadrilateral (39, 60, 52, 25), with diagonals 63 and 56, etc. He also introduces a proof of Ptolemy's theorem and in doing this follows Diophantus (\*iii\*, 19) in constructing from triangles (a, b, c) and (α, β, γ,) new triangles (aγ, bγ, cγ,) and (ac, β c, γ c,) and uses the actual examples given by Diophantus, namely (39, 52, 65) and (25, 60, 65). - [Previous: c7.45](https://indike.org/pramana/ins.science.kaye-1915.c7.45) - [Next: c7.47](https://indike.org/pramana/ins.science.kaye-1915.c7.47) - [Up: c7](https://indike.org/pramana/ins.science.kaye-1915.c7) ## Cites (1) - [Brāhmasphuṭasiddhānta](https://indike.org/pramana/in.astro.siddhanta.early.brahmasphutasiddhanta) — Brahmagupta, Sanskrit --- Source: [https://indike.org/pramana/ins.science.kaye-1915.c7.46](https://indike.org/pramana/ins.science.kaye-1915.c7.46) · Pramāṇa