Parts of a Circle - Problem 1   If you take just part of a
circle, that’s going to be considered an arc. So here I’ve drawn
arc ab which I can write as ab with an arc over it, so an arc is
the continous part of a circle between two end points. So if
you’d pick two points on a circle, an arc is all the points that
are in between those two endpoints and we measure that arc by
measuring the central angle. Well the central angle as it
probably sounds is centered at the centre of the circle, so if I
found the center of this circle containing that arc and I drew
in radii to the endpoints, this would be mu centre angle. So the
vertex of a central angle is at the centre of the circle.  Now
let’s say if measure x, a measure of this arc. If x is less than
180 degrees then we call that a minor arc. If x is equal to
exactly 180 degrees, half a circle, we call that a semicircle,
and last if x is greater than 180 degrees we call that a major
arc. So if you take just part of a circle, it’s going to be
considered an arc and