Εικόνες σελίδας
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II.
A right line is said to touch a circle, when drawn to the samé,
and being produced, does not cut the circle.
III. .

Circles are said to touch each other, which, meeting, do not cut
One another.
IV.

Right lines in a circle are said to be equally distant from the
center, when perpendiculars drawn from the center to each
of them are equal, and that line upon which the greatest
perpendicular falls is the least line.
- V.
Definition 19th, 1. - -
*VI.
An angle of a segment is the angle contained by the right line
and circumference of the circle.

VII.

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from some point in the circumference to the ends of that

olish is the base of the segment, which lines contain the angle, -

VIII. But,

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^^^) But, when the right lines containing the angle do receive any

& I.

b def. 15. 1. c A.K. 9. I.

part of the circumference, then the angle is said to stand upon
that circumference.
IX.

A seótor of a circle is that figure which is contained by two
right lines, drawn from the center, and the circumference be-
tween them.
X

Similar segments of circles are those which include equal angles or whereof the angles in them are equal.

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fible"; therefore, no point but F can be the centre. Where

fore, &c. -- -
Cor. Hence, if, in a circle, any right line cut another right

line into two equal parts, the centre of the circle will be in that

line which cuts the other into two equal parts.

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If any two points be assumed in the circumference of a circle, the right line joining these points will fall within the circle.

Let the circle be ABC, A and B the points in its circumference, the right line AB, joining these points, will fall within the circle. Find D the centre of the circle"; join DA, DB, and draw DF, cutting the right line AB in the point E.; then the right lines DA, DB, DF, are equal". But DF is greater than DE°; therefore, DA, DB, are likewise greater than DE; but lyP, DA, reach the circumference; therefore DE does not reach

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