Books Books The opposite angles of any quadrilateral figure described in a circle, are toe/ether equal to two right angles. Let ABCD be a quadrilateral figure in the circle ABCD : any two of its opposite angles are together equal to two right angles. Euclid in Paragraphs: The Elements of Euclid: Containing the First Six Books ... - Page 71
by Euclid - 1845 - 199 pages ## Descartes: Selected Philosophical Writings

René Descartes - Philosophy - 1988 - 276 pages
...cannot divide it, at least in our thought). And because of these facts it can be truly asserted that the three angles of every triangle are equal to two right angles and that every body is divisible. Fifthly, I ask my readers to spend a great deal of time and effort... ## Solutions of the Exercises in Tyler's Euclid

268 pages
...a quadrilateral have two of its opposite sides parallel, and the two others equal but not parallel, any two of its opposite angles are together equal to two right angles. In quad. ABCD let AD || BC and AB = DC. AD is not equal to BC, for then AB would be both equal to and... ## Calendar

University of Cambridge - 1844 - 550 pages
...quadrilateral be inscribable in two ellipses whose major axes are parallel or perpendicular to one another, any two of its opposite angles are together equal to two right angles. 4. A weight is supported by two pistons which are rigidly connected together, and which work in two... ## Life and Remains

564 pages
...We wish to recall that proposition. Arbitrary association of ideas immediately suggests the words, 'The three angles of every triangle are equal to two right angles.' But at first these are words only : our mind runs along an established train of sounds. By well-formed,... ## The American Mathematical Monthly: The Official Journal of the ..., Volume 7

Electronic journals - 1900 - 370 pages
...good only under the presupposition, that the constant is infinitely great. Only then is it true, that the three angles of every triangle are equal to two right angles ; also this can be easily proven if one takes as given the proposition, that the constant is infinitely... ## how we learn

...up. Nothing is taken on trust ; every step is understood and commands our intellectual assent. That the three angles of every triangle are equal to two right angles is a proposition which cannot be denied by anyone who has assented to the definitions and axioms which... 