A regular polygon.
There are always two angles between two radii of the same circle ... starting at one of them and going each direction to the other one. If you define the angle between them as the smaller of the two angles, then it can be anything between 0° and 180°. If you define it as the larger of the two, then it can be anything between 180° and 360°. If you don't care which of the two angles is measured, then it can be anything between 0° and 360°.
yes or no
sides
It is one measure - not the only one - of a "central tendency". It is the same as the "average". To calculate the average, just add all the numbers, and divide the result by the amount of numbers.
yes
Yes. All radii of the same circle have the same length.
Yes, providing that the radii are all in the same circle
Yes, all radii of a circle have the same length. One often thinks of the radius as being this length.
Yes, within the same circle
yes
No they have different heights and radii.
Yes providing that they are in the same circle
Yes, all radii of a given circle have the same length. A circle is defined as all the points on a plane that have a specified distance from a given point, called the center. Any segment from the center to the circle is called a radius (plural radii). Thus, by definition, all such segments (all radii) have the same length.
The plural of 'radius' is 'radii', not 'radiuses'. A circle has an infinite number of radii, but they are all of the same length.
NO. All the radii of a circle are of exactly the same length. In fact, that is the definition of the locus of a point describing a circle.
No. To be similar ALL lengths must be in the same ratio. If two cylinders have the same radii, but different heights then the radii have one ratio (1:1) but the heights have a different ratio; thus they are not similar.