Information AboutRuler |
| CATEGORIES ABOUT RULER | |
| dimensional instruments | |
| metalworking measuring instruments | |
| woodworking measuring instruments | |
| stonemasonary tools | |
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A ruler or '''rule''' is an Instrument used in Geometry , Technical Drawing and engineering/building to measure distances and/or to rule straight lines. Strictly speaking, the ''ruler'' is the instrument used to '''rule''' lines and the calibrated instrument used for determining measurement is called a ''measure''. However, common usage is that a ruler is calibrated so that it can measure. Several different designs of flexible instruments are used to determine length, such as the carpenter's rule, the ribbon-like tape measure used by tailors, and the retractable rule used especially in the construction trades and by home handyman, also known as a Tape Measure . As can be seen by the photos on this page, a 2 Metre carpenter's rule can be folded down to a length of only 20 Centimetres to easily fit in a pocket, and the 5 metre long tape easily retracts to fit within a small-sized housing. Practical rulers have distance markings along their edges.
GEOMETRIC CONSTRUCTIONS :''Main article: Compass And Straightedge In geometry, a ruler usually refers to an unmarked ruler, only used for drawing straight lines between points, not measuring. A Ruler And Compass Construction thus refers to constructions using such unmarked ruler and a compass. It is known for instance, that the Angle Trisection problem is an impossible one, within the classic restriction of ruler bearing no marks. However, should a single mark be allowed on the ruler, the problem becomes solvable. It is common to call rulers in the geometric context as Straightedge s. SEE ALSO
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