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CN. CT = "CA
74.9. Focus and directrix
Two lines from the bottom of p. 61, after rectangles insert under the segments.
p. 72, for Chap. VII. read Chap. VI.
p. 4, § 6, line 2, for except those contained, &c. read except those right angles contained by lines parallel and perpendicular to the line of intersection.
p. 14, § 7, line 3, for V and T read CV and CT.
p. 46, line 12 from the bottom, for diminishes the more read increases the more.
p. 55, line 4, for asymptotes read asymptote. References in Chap. VI. to Chap. V. should be to Chap. IV. p. 61, line 3 from the bottom, after rectangles insert under the segments. p. 72, for Chap. VII. read Chap. VI. p. 81, line 10 from the bottom, for SQP read SQP'. p. 82, line 8 from the bottom, for CR' read CR?. p. 87, for Chap. VIII. read Chap. VII. p. 91, line 4, for Chap. VI. read Chap. V.
If a straight line be drawn through two adjacent points of a curve, and the two points move towards one another on the curve until they coincide, the straight line in its final position is said to be a tangent to the curve at the point which it has finally in common with it.
2. In order to project a straight line AB (fig. $ 5) on a plane abc, we must draw the perpendicular Aa from some
J. C. S.