How to measure diameter of a circle if you near at hand have no tools necessary for this purpose? Actually, it is quite simple. For this purpose use the way described below.
It is required to you
- - A subject which diameter should be calculated.
- - Pencil or marker.
- - Ruler or roulette.
- - Sheet of paper, cardboard or plywood of the correct rectangular shape and the suitable size (see rice to a step 2).
Instruction
1. According to the theorem of the entered triangle from a school course of geometry, we know that the rectangular triangle can enter in any circle, as well as to describe a circle which tops will lie on its arch around a rectangular triangle.
2. Using this knowledge, take both objects: the one that has the form of a circle and the rectangular sheet of paper, cardboard or other material. And, the rectangular subject should have no rounded corners, it will allow to measure diameter of a circle quite precisely. The size of a rectangular subject has to be such that two of its opposite sides crossed a circle in two points.
3. According to the same theorem the hypotenuse (the party of a triangle opposite to a right angle) of a rectangular triangle will be equal to diameter of the circle described around it. For this purpose we take the sheet of cardboard or other rectangular subject, and we impose it on a circle so that a right angle? And rested the top against a circle arch as in the drawing.
4. Mark with a pencil or a marker those points in which the rectangle crosses a circle. In the drawing they are noted as points of E and F. Connect points of E and F straight line. This piece of EF is also diameter of our circle. Measure by its simple ruler or a roulette. Diameter of a circle is calculated.