Books Books When a straight line standing on another straight line makes the adjacent angles equal to one another, each of the angles is called a right angle; and the straight line which stands on the other is called a perpendicular to it. The First Book of Euclid's Elements, Simplified, Explained, and Illustrated ... - Page 6
by Euclides - 1847 ## The Young Mathematician's Guide: Being a Plain and Easy Introduction to the ...

John Ward - Mathematics - 1747 - 492 pages
...is, AC, and C J5, are Perpendicular to £> C, as well as -D, C is to /•j'r/W or both of them. g. An OBTUSE ANGLE is that which is greater than a Right Angle. Such is the Angle included between the Lines AC and n CB. 10. An ACUTE ANGLE is that ^_ which is lefs... ## The Elements of Euclid: The Errors, by which Theon, Or Others, Have Long Ago ...

Robert Simson - Trigonometry - 1762 - 466 pages
...angle ' at E.' X. When a ftraight line ftanding on another ftrailrht line makes the adjacent angles equal to one another, each of the angles is called a right angle; and the ltraight line which ftands on the other is called a perpendicular to it. • XI. An obtufe angle is... ## Instructions Given in the Drawing School Established by the Dublin Society ...

Joseph Fenn - Mathematics - 1769 - 536 pages
...When a ftraight line (AB) {landing on another ftright line (CD) makes the adjacent angles (ABD, ABC,) equal to one another, each of the angles is called a right angle ; and the rtraight line (AB) which ftands on the other (CD) is called я perpendicular. Fig. 7. XI. An Obtvfe... ## The Elements of Euclid, Viz: The Errors, by which Theon, Or Others, Have ...

Robert Simson - Trigonometry - 1775 - 520 pages
...the angle at li.' X. When a ftraight line flanding on another ftraight line makes the adjacent angles equal to one another, each of the angles is called a right angle ; and the ftraight line which flands on the other is called a perpendicular to it. — XI. An obtufe angle is... ## The First Six Books: Together with the Eleventh and Twelfth

Euclid - 1781 - 550 pages
...the Angle at E.' .X. When a ftraight line flanding on another ftraight line makes the adjacent angles equal to one another, each of the angles is called a right angle ; and the ftraight line which ftands on the other is called a perpendicular to it. XI. An obtufe angle is that... ## The philosophical and mathematical commentaries of Proclus ... on the first ...

Proclus (Diadochus.) - 1788 - 350 pages
...and the infifting Right Line, is called a PERPENDICULAR to that upon which it ftands. DEFINITION Xf. An OBTUSE ANGLE is that which is greater than a RIGHT ANGLE. DEFINITION XII. But an ACUTE ANGLE, is that which is Icfs than a RIGHT ANGLE, THESE are the triple... ## Observations on the Nature of Demonstrative Evidence: With an Explanation of ...

Thomas Beddoes - Geometry - 1793 - 196 pages
...otherwife. DEFINITION X, When a Jlfaight line ftanding on another Jiraight line makes the adjacent angles equal to one another, each of the angles is called a right angle, and the line which Jlands on the other is called a perpendicular to it. Here we have an appeal made to the... ## Elements of Geometry: Containing the First Six Books of Euclid, with Two ...

John Playfair - Trigonometry - 1795 - 444 pages
...E.' VII. •/ f * When a ftraight line ftanding on another ftraight line makes the adjacent angles equal to one another, each of the angles is called a right angle ; and the ftraight line which ftands on the other is called a per- , pendicular to it. VJII vra. Ao obtufe angle... ## The Elements of Euclid: Viz. the First Six Books, with the Eleventh and ...

Alexander Ingram - Trigonometry - 1799 - 351 pages
...the angle at E.X. When a ftraight line ftanding on another ftraight line makes the adjacent angles equal to one another, each of the angles is called a right angle ; and the ftraight line which ftands on the other is called a perpendicular to it. XI. An oUufe angle is that... 