<XOY is a given angle which has to be trisected.
Draw a circle "O" intersecting OX and OY at A and B respectively.
Joi A, B. Draw a semi circle on AB, AB diameter and P center.
Divide the semi circle at C, D such that arc AC = arc CD = arc DB = radius AP
Join O,C and O,D. OC and OD intersect arc AB at E and F.
OA = OE = OF = OB (radii of circle O)
arc AB and semi circle are standing on the same straight line AB.
Further arc AC = arc CD = arc DB (construction)
Arc AE = arc EF = arc FB (experimental conclusion) I'm not familiar with "experimental conclusion" as a reason in a geometric proof ... ???
These arcs subtant <AOE, <EOF, <FOB which are equal as equal arcs subtant equal angles at the centre
Therefore <AOE = <EOF = <FOB
Hence the trisection
Mohd Shafiuddin Ahmed
Ganapavaram - village & post
Kodad mandal - Nalagonda District
Andhra Pradesh, India - PIN - 508206