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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

## Elements of Geometry: Containing the First Six Books of Euclid, with a ...

John Playfair - Euclid's Elements - 1842 - 332 pages
...angle ; wherefore the other ADC is greater 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,...

## Euclid in Paragraphs: The Elements of Euclid: Containing the First Six Books ...

Euclid - Geometry - 1845 - 218 pages
...angle of the less segment is said to be less, than a right angle.' COB. 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 First Six, and the Eleventh and Twelfth Books of Euclid's Elements: With ...

Euclid, James Thomson - Geometry - 1845 - 380 pages
...3. If a triangle have a right angle, the remaining angles are together equal to a right angle : and if one angle of a triangle be equal to the other two, it is a right angle. Cor. 4. The angles at the base of a right-angled isosceles triangle are each half a right angle. Cor....

## Euclid's Elements of geometry [book 1-6, 11,12] with explanatory notes ...

Euclides - 1845 - 544 pages
...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 ; (i. 32.) and when the adjacent angles...

## Elements of Geometry: Containing the First Six Books of Euclid, with a ...

John Playfair - Euclid's Elements - 1846 - 332 pages
...angle ; wherefore the other ADC is greater 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 Elements of Euclid, the parts read in the University of Cambridge [book ...

Euclides - 1846 - 292 pages
...semicircle, is greater than a right angle. Wherefore, The angle tyc. QED 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,...

## Euclid's Elements: Or, Second Lessons in Geometry,in the Order of Simson's ...

Dennis M'Curdy - Geometry - 1846 - 168 pages
...they are equal two and two: therefore EBA and ECA are equal to EAB and EAC, or the whole angle BAC. But if one angle of a triangle be equal to the other two, it must be a right angle (4); therefore BAC, an angle in a semicircle, is a right angle, as stated. gle:...

## The Elements of Geometry, Symbolically Arranged

Great Britain. Admiralty - Geometry - 1846 - 130 pages
...trapezium to the 4 angles, is the least, when that point is the intersection of the diameters. 32. If one angle of a triangle be equal to the other two together, it is a right angle. 33. The diameters of a rhombus bisect each other at right angles. 34....