In this section, you learn to find the arc length and area of a sector of a circle and tackle problems involving apparent size. But before you do so, you need to be familiar with some related terminology and formulas.
A sector of a circle is the region bounded by a central angle and the intercepted arc.
In the preceding figure, the sector of the circle is the shaded region. It is clear that the length of the arc is some fraction of the circle’s circumference and the sector’s area is some fraction of the circle’s ...