Equal angles of incidence and reflection at a circle
A geometric proof, with a perpendicular that curves toward line c s
The sheet argues, with lettered diagrams of triangles and lines set against circles, that the spaces or angles of incidence formed between a circle and the incident and reflected lines are always equal to one another. A companion note treats how a straight perpendicular upon the line n m curves toward the line c s, the curvature growing as c s grows shorter than h m. Further faint jottings and a small sketch at the upper right, together with a central lettered figure, are present on the leaf but are not part of the transcription given here.
On this page
Incident and reflected angles about a circle are equal
The spaces, or angles, of incidence created between the circle and the incident and reflected line are always equal to one another outside the circumferential line, and equal too are the angles generated within that circumferential line. The proposition closes with the single word 'it is proved'.
A perpendicular on line n m curving toward c s
The straight perpendicular upon the straight line n m curves toward the line c s with as much greater curvature as the line c s is less than the line h m. The relation ties the amount of bending to the ratio of the two segments.