Barrow, Isaac - Lectiones opticae & geometricae : in quibus phaenomenon opticorum genuinae rationes investigantur, ac exponuntur: et generalia curvarum linearum symptomata declarantur

Scan	Original
41	23
42	24
43	25
44	26
45	27
46	28
47	29
48	30
49	31
50	32
51	33
52	34
53	35
54	36
55	37
56	38
57	39
58	40
59	41
60	42
61	43
62	44
63	45
64	46
65	47
66	48
67	49
68	50
69	51
70	52

8769

Lect. X.

1. IN poſtrema Lectione quod ſpectavimus punctum circuli convexo
alluxit; nunc parte@ concavas irradians aliud, at magìs @ π’ π ω,
contemplabimur. & quidem caſuum præcipuorum diverſitatem im-
primìs diſtinguemus. Nempe radiet punctum A in circulum re-
flectentem, cujus centrum C; connexaque recta AC protendatur in-
definitè; quo poſito.

II. 1. Incidat radius AN; & ſit AN = AC; erit ipſius AN
reflexus, puta N _a_, ad AC parallelus.

11Fig. 97.

Hoc è ſuprà generatim oſtenſis conſtat; & facilè jam patet, con-
nexâ CA. etenim eſt ang. ACN = AN C; ob AC, AN, ex
Hypotheſi pares; & ang. ANC = _a_ NC, propter reflectionem;
adeóque ang. ACN = _a_ NC; unde ſunt AC, N _a_ ſibi paralle-
læ.

III. 2. Incidat radius AM major ipsâ AC; ejus reflexus (puta
22Fig. 98. M _a_) cum axe directè procedens conveniet ultra centrum, reſpectu
puncti A; (hoc eſt centrum C puncto radianti, concurſuique inter-
jacebit).

Nam ob AM & gt; AC, erit ang. ACM& gt; AMC = CM _a_.
ergo ang. BCM+ CM _a_ & lt; ang. BCM+ ACM = 2 rect.
quare M _a_, CB convenient infra CM ad partes _a_ B; velut
ad K.

IV. 3. Incidat radius AR; & ſit AR minor ipsâ AC; ejus
33Fig. 99. reflexus, puta R _a_, axi retrò protractus occurret. (hoceſt ut radians
centro, concurſuíque ſit interjectum).

Nam hîc ob AR & lt; AC; erit ang. ACR& lt; ang ARC = ang.
_a_ RC. quapropter ang. DCR+ _a_ RC & gt; 2 rect. unde patet ipſas
D C, _a_ R portractas infra CR concurrere.

Page concordance

Text layer

Text normalization

Search

Scan	Original
41	23
42	24
43	25
44	26
45	27
46	28
47	29
48	30
49	31
50	32
51	33
52	34
53	35
54	36
55	37
56	38
57	39
58	40
59	41
60	42
61	43
62	44
63	45
64	46
65	47
66	48
67	49
68	50
69	51
70	52

Scan	Original
41	23
42	24
43	25
44	26
45	27
46	28
47	29
48	30
49	31
50	32
51	33
52	34
53	35
54	36
55	37
56	38
57	39
58	40
59	41
60	42
61	43
62	44
63	45
64	46
65	47
66	48
67	49
68	50
69	51
70	52

Scan	Original
41	23
42	24
43	25
44	26
45	27
46	28
47	29
48	30
49	31
50	32
51	33
52	34
53	35
54	36
55	37
56	38
57	39
58	40
59	41
60	42
61	43
62	44
63	45
64	46
65	47
66	48
67	49
68	50
69	51
70	52