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# Title: [Philosophiae Naturalis Principia Mathematica] Philosophiæ Naturalis Principia Mathematica (shelfmark Leibn. Marg. 166)
# Folio 206, page id 1041163592:0240
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PTTTLOSODIILL NATVRALIS
DROPOSITIO ZCVT. THEOREMA L.
Tisdem positis es quod motus ante incidentiam velocior sit quam
postea: dico quod corpus, inclinando lineam incidentiae, refle-
Etetur tandem, e angulus reftexionis fiet aequalis anculo inci-
dentiae.
Nam concipe corpus inter parallela plana Aa, Bb, C.6, dec. c
Scribere arcus Parabolicos, ut supra; sintque arcus illi FTF
2
R, _C. EF sic ca lincae incidentiae CF F obliquitas ad planum pri-
num a, ut sinus incidentia sic ad radium circuli, cujus est fnUS,
in ea ratione quam habet idem linus incidentiae ad Cinum eper-
sentixe ex plano D d in spatium D de F: ec ob linum cmeroen-
cixe jam factum aequalem radio, angulus emersentix erit rectus, ad-
eoque linea emergentiae coincidet cum plano D d. Perveniat cor-
Dus ad hoc planum in puncto R; e quoniam linca emergentix
coincidit cum eodem
plano, perspicuum est
Quod corpus non po:
rest ultra Pergere ver
sus planum L. c. Sc
nec potest idem perse
re in linca emergentix
Rd. Propterea quoc
perpetuo aecrahitur vel impCIMLa VersuS MIC
verretur itaque inter plana CC, D a describendo arcum Parabole
)R9. cujus vertex principalis (juxta demonstrata Cahlaei) est in
R; lecabit planum Cc in eodem angulo in qg. ac prius i e; dein
pergendo in arcubus parabolicis qp. ph, dcc. arcubus prioribus
)D DI Smilibus e aequalibus, secabit reliqua plana in iildem
angulis in po h, ecc. ac prius in P, FI, _c. emersetque tandem ca-
dem obliquitare in h, qua incidit in fI. Concipe jam planorum
Aa Bb, CC, D d F. e, _c. incervalla in intinicum minui de nume.
rum augeri, co uc actio accractionis rel impullus secundum legem
quamcunque assignatam continua reddatur; ec angulus emersen-
rixe semper angulo incidentix aequalis existens, eidem cciamnum
manebir aequalis. 8. F. D.
2I
Tiu
ntIX. RC.
206
Scholium.
DE MOXV
EORPORVM