 | John Playfair - Mathematics - 1806 - 320 pages
...the same straight line with CB. Wherefore, if at a point, &c. QED PROP. XV. THEOR. IF two straight lines cut one another, the vertical, / or opposite, angles shall be equal. Let the two straight lines AB, CD cut one another in the point E ; the angle AEC shall be equal to... | |
 | Robert Simson - Trigonometry - 1806 - 546 pages
...the same straight line with CB. Wherefore, if at a point, &c. QED PROP. XV. THEOR. IF two straight lines cut one another, the vertical, or opposite, angles shall be equal. Let the two straight lines AB, CD cut one another in the point E ; the angle AEC shall be equal to... | |
 | John Mason Good - 1813 - 714 pages
...these two straight lines •hall be in one and the same straight line. Piop. XV. Theor. If two straight lines cut one another, the vertical, or opposite, angles shall be equal. Prop. XVt Theor. If one side of a triangle be produced, the exterior angle is greater than «jtherof... | |
 | Peter Nicholson - Mathematics - 1825 - 1046 pages
...straight line with CB. Wherefore, if at э point, &c. Q. £. D. Proposition ХУ. Theorem. If two straight lines cut one another, the vertical, or opposite, angles shall be equal. . Let the two straight lines AB, CD, cut one another in the point £ ; the angle ABC shall be equal... | |
 | Robert Simson - Trigonometry - 1827 - 546 pages
...the same straight line with CB. Wherefore, if at a point, &c. QED PROP. XV. THEOR. If two straight lines cut one another, the vertical, or opposite, angles shall be equal. Let the two straight lines AB, CD, cut one another in the point E : the angle AEC shall be equal to... | |
 | Pierce Morton - Geometry - 1830 - 584 pages
...Cor. 2. Any angle of a triangle is less than two nght angles. PROP. 3. (Eue. L 15.) ff two straight lines cut one another, the vertical or opposite angles shall be equal. Let the two straight «, lines А В, С D, cut / one another in the х/ point E : the vertical u angles... | |
 | Mathematics - 1835 - 684 pages
...Cor. 2. Any angle of a triangle is less than two right angles. PKOP. 3. (Eue. i. 15.) If two straight lines cut one another, the vertical or opposite angles shall be equal. Let the two straight . lines AB, CD, cut J* one another in the к/ point E : the vertical angles A... | |
 | Euclid - 1835 - 540 pages
...the same straight line with.CB. Wherefore, " if at a point," &c. QED PROP. XV. THEOR. If two straight lines cut one another, the vertical, or opposite, angles shall be equal. Let the two straight lines AB, CD, cut one another in the point E; the angle AEC shall be equal to... | |
 | John Playfair - Geometry - 1836 - 148 pages
...In the same manner it can be shewn, that the angles AED, BEC are equal. Therefore, if two straight lines cut one another, the vertical or opposite angles shall be equal. Which was to be proved. COR. I. If two straight lines cut one another, the four angles" which they... | |
 | Euclides - Euclid's Elements - 1837 - 112 pages
...similarly* no other line but BD is in the same right line with BC. PROPOSITION XV. Theorem. If two straight lines cut one another, the vertical, or opposite, angles shall be equal. Steps of the Demonstration. 1. Prove that Zs AEC + AED = 2 right Zs, 2. that Zs AED + DEB = Zs AEC... | |
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IF two straight lines cut one another, the vertical, or opposite, angles shall be equal. 
