Mechanical drawing : a manual for teachers and students (1902)
Cross, Anson Kent · Boston : Ginn & Co. · leaf 26
Problem 21,— To inscribe a circle within a giventriangle ABC. By Problem 10, bisect any two angles of thetriangle, as CAB and ABC. The bisecting linesintersect at i, the centre of the required circle. Aperpendicular, as 1-2, from i to any side of the tri-angle, is the radius of the required circle.…
Mechanical drawing
Internet Archive · Boston Public Library · Public Domain Mark 1.0. Free to use for anything.
![An illustration from Nicolai Copernici Torinensis De reuolutionibus orbium coelestium, libri VI : Habes in hoc opere iam recens nato, & aedito, studiose lector, motus stellarum, tam fixarum, quàm erraticarum, cum ex ueteribus, tum etiam ex recentibus obseruationibus restitutos: & nouis insuper ac admirabilibus hypothesibus ornatos. Habes etiam tabulas expeditissimas, ex quibus eosdem ad quoduis tempus quàm facillime caculare poteris. Igitur eme, lege, fruere. [Line in Greek] (1543)](https://img.insideoutlibrary.com/img/200/ia-nicolaicopernici00cope-193-112.webp)
