Concentric circles are circles with the same common centre.
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I believe that is called a Scalene triangle.
A line segment drawn through the centre of a circle and having endpoints on the circumference of that circle is called the diameter. Notably, a line segement with one endpoint at the centre of the circle and one anywhere on the circumference of the circle is called the radius, and is exactly half the length of the diameter.
Two vectors having same magnitude but different direction are called equivalent vectors.
equivalent
Copernicus's system used circles and epicycles, just like the ancient Ptolemaic system, with the difference that by placing the Sun at the centre Copernicus could simplify the complicated paths taken by the planets through space. Kepler had the advantage of new accurate observations made by Tycho Brahe at the end of the 16th century, and these enabled Kepler to realise that by using elliptical orbits for the planets, the modelled positions could be fitted more closely with the measured positions. Kepler retained the idea of having the Sun at the centre and it is the model used today with slight modifications from Einstein's theory of relativity.