How to measure the diameter of a circle if you do not have the tools you need? In fact, it's pretty simple.
To do this, use the method described below.
You will need
- - The object whose diameter is to be calculated.
- - A pencil or a marker.
- - Ruler or ruler.
- - A sheet of paper, cardboard or plywood of regular rectangular shape and of suitable size (see the pic to step 2).
According to the inscribed triangle theorem fromSchool course of geometry, we know that a rectangular triangle can be inscribed in any circle, as well as describe a circle around a rectangular triangle whose vertices lie on its arc.
Using this knowledge, take both subjects: One that has the shape of a circle and a rectangular sheet of paper, cardboard, or other material. Moreover, the angles of a rectangular object should not be rounded, this will allow us to measure quite accurately diameter Circle. The size of a rectangular object should be such that its two opposite sides intersect the circle at two points.
According to the same hypotenuse theorem (the side of the triangle opposite to the right angle) of a right-angled triangle is equal to diameterWith the circle circumscribed around it. To do this, take a sheet of cardboard or another rectangular object, and superimpose it on the circle so that the right angle? Its apex A rested against the arc of the circle as in the figure.
Mark the points in which the rectangle crosses the circle with a pencil or marker. In the figure, they are marked as points E and F. Connect points E and F by a straight line. This segment of EF is diameter Our circle. Measure it with a simple ruler or tape measure. The diameter of the circle is calculated.