Straightedge

This article is about the tool used in geometry. For information on the subculture of the same name, you may want Straight edge instead.

---

A straightedge is a tool similar to a ruler, but without markings.

An straightedge is used in ruler-and-compass constructions. It may be used to:

• Given two points, draw the line connecting them.
• Given a point and a circle, draw either tangent.
• Given two circles, draw any of their common tangents.

It may not be marked or used together with the compass so as to transfer the length of one segment to another.

It is possible to do all straightedge-and-compass constructions without the straightedge. That is, it is possible, using only a compass, to find the intersection of two lines given two points on each, and to find the tangent points to circles. It isn't, however, possible to do all constructions using only a straightedge. It is possible to do them by drawing one circle and its center, then using only the straightedge.

Making a straightedge

A real-world straightedge is a practical tool that approximates the idealized mathematical object described above.

Making a practical straightedge without access to a pre-existing straightedge or modern machine tools is an interesting problem in mechanical engineering. One way of doing this is to make a high-quality flat surface first, engineer's blue and polishing techniques, then to shape the straightedge so as to lie flat along the flat surface.

The method of producing accurate flat surfaces using three trial surfaces was invented by Sir Joseph Whitworth in 1830.

Another way of doing this is described in the link at the end of the article.

References:

• Wayne R. Moore, Foundations of Mechanical Accuracy, Moore Special Tool Company, Bridgeport, CT (1970)

External links

• http://www.tdl.com/~swensen/machines/straight_edge/straight_edge.html

Common misspelling and questions (FAQ)

traightedge  sraightedge  staightedge  strightedge  straghtedge  straihtedge  straigtedge  straighedge  straightdge  straightege  straightede  straightedg  tsraightedge  srtaightedge  starightedge  striaghtedge  stragihtedge  straihgtedge  straigthedge  straighetdge  straightdege  straightegde  straightedeg  straightedg  sstraightedge  sttraightedge  strraightedge  straaightedge  straiightedge  straigghtedge  straighhtedge  straighttedge  straighteedge  straighteddge  straightedgge  straightedgee  wtraightedge  atraightedge  ztraightedge  etraightedge  xtraightedge  etraightedge  dtraightedge  xtraightedge  s5raightedge  srraightedge  sfraightedge  s6raightedge  sgraightedge  s6raightedge  syraightedge  sgraightedge  st4aightedge  steaightedge  stdaightedge  st5aightedge  stfaightedge  st5aightedge  sttaightedge  stfaightedge  strqightedge  strwightedge  strzightedge  strwightedge  strsightedge  strzightedge  stra8ghtedge  straughtedge  strajghtedge  stra9ghtedge  strakghtedge  stra9ghtedge  straoghtedge  strakghtedge  straithtedge  straifhtedge  straivhtedge  straiyhtedge  straibhtedge  straiyhtedge  straihhtedge  straibhtedge  straigytedge  straiggtedge  straigbtedge  straigutedge  straigntedge  straigutedge  straigjtedge  straigntedge  straigh5edge  straighredge  straighfedge  straigh6edge  straighgedge  straigh6edge  straighyedge  straighgedge  straight3dge  straightwdge  straightsdge  straight4dge  straightddge  straight4dge  straightrdge  straightddge  straighteege  straightesge  straightexge  straighterge  straightecge  straighterge  straightefge  straightecge  straightedte  straightedfe  straightedve  straightedye  straightedbe  straightedye  straightedhe  straightedbe  straightedg3  straightedgw  straightedgs  straightedg4  straightedgd  straightedg4  straightedgr  straightedgd  strayghtedge  syraightedge  styraightedge  straightedges 


It is folly to attempt to ignore the fact that the follow me. It is a dreary drive over the hills to the pest-house. office. Our proposed visitation has been telephoned to the resident lonesome slope of a suburban hill. As we get into the rugged edge of the population, we ask our way to the pest-house. Yonder it lies, surrounded with clamorous water-fowl, but now all, all under the spell of the hill-slope, sown thick with stones, and stops short at the great solid so call it. We ring the dreadful bell - the passing-bell, that is seldom living death. The doctor welcomes us to an enclosure that is utterly whitewashed; the with the lazaret is of the cheapest description; there is a primitive reminds one of a chill December in a desert island. Cheap as it is and the plague in its present stage of development. The doctor has weeded eucalyptus, and has already a little plot of flowers by the office pest-house is set apart for the exclusive use of the Chinese lepers, who one after another, and then we take them all in at a glance, or group character of their physical hideousness. They are not all alike; with some the flesh has begun to wither and.