# Marks' First Lessons in Geometry: In Two Parts : Objectively Presented and Designed for the Use of Primary Classes in Grammar Schools, Academies, Etc

Ivison, Blakeman, Taylor,, 1871 - 157 СЕКъДЕР

### тИ КщМЕ ОИ ВЯчСТЕР -сЩМТАНГ ЙЯИТИЙчР

дЕМ ЕМТОПъСАЛЕ ЙЯИТИЙщР СТИР СУМчХЕИР ТОПОХЕСъЕР.

### дГЛОЖИКч АПОСПэСЛАТА

сЕКъДА 74 - PERIPHERY of a circle is its entire bounding line ; or it is a curved line, all points of which are equally distant from a point within called the center.
сЕКъДА 24 - An ACUTE ANGLE is one which is less than a right angle ; as the angle DEF.
сЕКъДА 147 - If two triangles have the three sides of the one equal to the three sides of the other, each to each, the triangles are congruent.
сЕКъДА 88 - Things which are double of the same thing, are equal to each other. 7. Things which are halves of the same thing, are equal to each other. 8. The whole is greater than any of its parts. 9. The whole is equal to the sum of all its parts. 10. All right angles are equal to each other. II. From one point to another, only one straight line can be drawn.
сЕКъДА 25 - Then it is called an acute angle. An acute angle is one which is less than a right angle.
сЕКъДА 83 - A segment bounded by a diameter and a semicircumference is a "semicircle." A semicircle is half a circle. Read four segments each larger than a semicircle. The part of the circle between the two radii of, oi, and the arc/z, is called a
сЕКъДА 152 - PROPOSITION XXII. THEOREM. DEMONSTRATION. We wish to prove that The angle formed by a tangent and a chord meeting at the point of contact is measured by half the intercepted arc. Let the tangent CAB and the chord AD meet at the point of contact A ; then will the angle BAD be measured by half the intercepted arc A D. For draw the diameter AE F. Because AB is a tangent, and AE a radius at the point of contact, the angle BAF is a right angle, and is measured by the semicircle AD F.