55) What is a plane figure bound by a curve formed by the locus of a point that moves so that it is always at a fixed distance from a stationary point is its centre?

56) What is the liner length of the entire curve that is equal to Pi x D? (D is the diameter)

57) What is the part of circle between any points on its circumference of periphery?

58) What is the term for longest chord of a circle?

59) What is the term for a straight line joining ends of an arc on a circle?