Diameter of a circle is a chord which passes through the center of this circle and connects couple of points of this geometrical figure most remote among themselves. Also diameter is called length of a chord which is equal to two radiuses.
Instruction
1. In geometry under diameter of conic section accept a straight line which passes through the middle of two parallel chords. In case of consideration of a parabola all its diameters are parallel to its main axis. Determination of diameter as lengths of a certain piece is also applied to other geometrical figures. In this case diameter of a figure should be considered the top side of distance between all possible couples of points of this figure. So, diameter of an ellipse - it is any the taken chord which passes through its center, it will be equal to length of its biggest axis. The interfaced diameter of an ellipse consider 2 of its diameters which have to have a certain property: the middle of chords which are parallel to 1 diameter are located on the 2nd diameter. Then the middle of the chords parallel to the 2nd diameter are located on 1 diameter. If the ellipse is applied as an image of a circle at affine transformation, then its diameters will be the images of 2 diameters of this circle located at an angle in 90 degrees.
2. Diameter of a hyperbole consider the chord passing through the center of this hyperbole. The interfaced its diameters consider diameters which middle of chords go parallel to its first diameter, are on the second diameter. And the middle of chords which go parallel to its second diameter is on the first diameter.
3. Certain tasks in geometry require determination of diameter of a square which is equal to length of its diagonal. The relation of length of a certain circle to its diameter is standard for all circles. This relation equals to number p, equal 3.1415...
4. It is possible to determine the area of a circle by diameter. For this purpose it is necessary to increase the squared numerical value of diameter of the defined figure by number p (3.14) and to divide the received number into 4.
5. Except geometry, the concept of diameter is applied also in astronomy. The cross size of the planet is considered true diameter. Besides true, allocate the visible diameter which is defined as the cross size in degrees defining a corner under which the required planet is visible to the researcher - i.e. these are the angular sizes of the defined object.