Constructing With Only Ruler or Only Compass
It is possible (according to the Mohr–Mascheroni theorem) to construct anything with just a compass if it can be constructed with a ruler and compass, provided that the given data and the data to be found consist of discrete points (not lines or circles). It is impossible to take a square root with just a ruler, so some things that cannot be constructed with a ruler can be constructed with a compass; but (by the Poncelet–Steiner theorem) given a single circle and its center, they can be constructed.
Read more about this topic: Compass And Straightedge Constructions
Famous quotes containing the words constructing, ruler and/or compass:
“The very hope of experimental philosophy, its expectation of constructing the sciences into a true philosophy of nature, is based on induction, or, if you please, the a priori presumption, that physical causation is universal; that the constitution of nature is written in its actual manifestations, and needs only to be deciphered by experimental and inductive research; that it is not a latent invisible writing, to be brought out by the magic of mental anticipation or metaphysical mediation.”
—Chauncey Wright (1830–1875)
“Who made you a ruler and judge over us?”
—Bible: Hebrew, Exodus 2:14.
Hebrews to Moses.
“It is cruel for you to leave your daughter, so full of hope and resolve, to suffer the humiliations of disfranchisement she already feels so keenly, and which she will find more and more galling as she grows into the stronger and grander woman she is sure to be. If it were your son who for any cause was denied his right to have his opinion counted, you would compass sea and land to lift the ban from him.”
—Susan B. Anthony (1820–1906)