CHAPTER15 Circles ..........................................................................................
In This Chapter
- Exploring the properties
of circles - Measuring angles in and
around the circle - Investigating lines and seg-
ments that interact with
circles - Finding the area and
circumference of circles - Connecting a circle drawn
on the coordinate plane to
an equation
Triangles, quadrilaterals, pentagons, hexagons, and all the
figures you’ve learned about so far have one thing in common:
line segments. All polygons are built from line segments that
form their sides and meet to form their angles. But the world
of geometry isn’t all straight lines.
Around the world of geometry, you’ll find lots of things that
are round, things that curve. The basic shape that forms the
basis of all things that curve is the circle. In this chapter,
you’ll meet the circle and all the lines and angles that are
associated with it. You’ll get to know what those lines tell
you about the circle and see how they relate to the familiar
triangle. You’ll learn how to measure the angles, and find
out how they relate to the circle and to one another. And just
as you learned to find the perimeter and area of a polygon,
you’ll explore how to measure the distance around a circle
and how to measure the space inside it.