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From this it is manifest, that if one angle of a triangle be equal to the other two, it is a right angle, because the angle adjacent to it is equal to the same two; and when the adjacent angles are equal, they are right angles.
A Royal Road to Geometry: Or, an Easy and Familiar Introduction to the ... - Page 178
by Thomas Malton - 1774 - 440 pages

## The Elements of Euclid [book 1] for beginners, by J. Lowres

Euclides - 1852 - 48 pages
...therefore the three interior angles, CBA, CAB, and ACB, are equal to two right angles. WWD COB. 1. If one angle of a triangle be equal to the other two angles, it is a right angle. COB. 2. A perpendicular may be drawn from the end of a line, by describing...

## The geometry, by T. S. Davies. Conic sections, by Stephen Fenwick

Royal Military Academy, Woolwich - Mathematics - 1853 - 400 pages
...angle of the less segment is said to be less, than a right angle.' COn. From this it is manifest, that if one angle of a triangle be equal to the other two, it is a right angle, because the angle adjacent to it is equal to the same two ; and whim the adjacent angles are txjnal,...

## The first six books of the Elements of Euclid, with numerous exercises

Euclides - Geometry - 1853 - 176 pages
...angle of the less segment is said to be less, than a right angle. COR. From this it is manifest that if one angle of a triangle be equal to the other two it is a right angle, because the angle adjacent to it is equal to the same two ; and when the adjacent angles are equal...

## The synoptical Euclid; being the first four books of Euclid's Elements of ...

Euclides - 1853 - 146 pages
...of the less segment is said to be less, than a right angle." COK. — From this it is manifest, that if one angle of a triangle be equal to the other two, it is a right angle, because the angle adjacent to it is equal (I, .32.) to the same two ; and when the adjacent angles...

## The Elements of Euclid: With Many Additional Propositions ..., Part 1

Euclid - Geometry - 1853 - 176 pages
...tchol. 3. 1.47 I. 47, cor. 8. . HYPOTHESES. If any three angles are the internal angles of a triangle. If one angle of a triangle be equal to the other two. If one angle of a triangle be a right angle. Idem If two angles of a triangle are equal. If in any...

## The Elements of Euclid. Books I.-VI.; XI. 1-21 XII. 1-2. A New Text ..., Book 1

Euclides - Geometry - 1853 - 334 pages
...the segment less than a semicircle is greater than a right angle. Which was to be proved. COB. — If one angle of a triangle be equal to the other two : then it shall be a right angle. 'For let ABC be a triangle, one of the angles of which BAC is equal...

## The Elements of geometry; or, The first six books, with the eleventh and ...

Euclides - 1855 - 262 pages
...is greater than a right angle. Therefore, in a circle, &c. QED Сon. From this it is manifest, that if one angle of a triangle be equal to the other two, it is a right angle : because the angle adjacent to it is equal (I. 32) to the same two ; and when the adjacent angles...

## Euclid's Elements of Geometry: Chiefly from the Text of Dr. Simson, with ...

Robert Potts - Geometry, Plane - 1860 - 380 pages
...in a circle the angle in a semicircle is a right angle ; &c. QED Con. From this it is manifest, that if one angle of a triangle be equal to the other two, it is a right angle : because the angle adjacent to it is equal to the same two ; (I. 32.) and when the adjacent angles...