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If, at a point in a straight line, two other straight lines, upon the opposite sides of it, make the adjacent angles together equal to two right angles, these two straight lines shall be in one and the same straight line.
The Elements of Geometry, Symbolically Arranged - Page 21
by Great Britain. Admiralty - 1846

## Lessons on Form: Or, An Introduction to Geometry, as Given in a Pestalozzian ...

Charles Reiner - Geometry - 1837 - 246 pages
...which are these interior angles. 24. If, at one point in a straight line, two other straight lines make the adjacent angles, together, equal to two right angles, these two lines are in the same straight line. SECTION III. ONE TRIANGLE. M. — State all you have learnt concerning...

## A companion to Euclid: being a help to the understanding and remembering of ...

Euclides - Euclid's Elements - 1837 - 112 pages
...3. that Zs DBA + ABC = the two rt. Zs CBE + EBD. PROPOSITION XIV. (Argument ad absurdum). Theorem. If, at a point in a straight line, two other straight lines on opposite sides of it make the adjacent angles together equal to two right angles, these two straight...

## The Elements of Euclid

Euclid - Geometry - 1838 - 478 pages
...are together equal to two right angles. Wherefore, when a straight line, &c. Q,. ED PROP. XIV. THEOR. IF, at a point in a straight line, two other straight...opposite sides of it, make the adjacent angles together etlual to two right angles, these two straight lines shall be in one and the same straight line. n...

## Euclid's Elements [book 1-6] with corrections, by J.R. Young

Euclides - 1838 - 264 pages
...of it, 'make tlic adjacent angles together equal to two right angles, these tiro straight line • shall be in one and the same straight line. At the point B in the straight line AB, let the two straight lines BC, BD upon the opposite sides of AB, make the adjacent...

## The Elements of Euclid; viz. the first six books,together with the eleventh ...

Euclides - Geometry - 1841 - 378 pages
...therefore DBA, ABC are together equal to two right angles. Wherefore, the angles, &c. QED PROP. XIV. THEOR. If, at a point in a straight line, two other straight...one and the same straight line. At the point B in the straight line AB, let the two straight lines ( A BC, BD upon the opposite sides of AB, make the...

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

John Playfair - Euclid's Elements - 1842 - 332 pages
...angles ; because their sum is equal to that of the two adjacent angles DBA, ABC. PROP. XIV. THEOR. If, at a point in a straight line, two other straight...equal to two right angles, these two straight lines are in one and the same straight line. At the point B in the straight line AB, let the two straight...

## Elements of geometry: consisting of the first four,and the sixth, books of ...

Euclides - 1842 - 320 pages
...any number of lines meeting in one point, are together equal to four right angles. PROP. XIV. THEOR. straight lines shall be in one and the same straight line. At the point в in the straight line AB, let the two straight lines вc, BD upon the opposite sides of AB make the...

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

Euclides - 1845 - 544 pages
...to two right angles, (ax. 1.) Wherefore when a straight line, &c. QE ». PROPOSITION XIV. THEOREM. If at a point in a straight line, two other straight...one and the same straight line. At the point B in the straight line AB, let the two straight lines BC, BD upon the opposite sides of AB, make the adjacent...