#### Math - 2019-20

# 5.10 - Circles

**The
student will **

**identify**and**describe**the diameter, radius, chord, and circumference of a circle.

*Adopted: 2016*

### BIG IDEAS

- So that I
can design circular objects such as camera lenses, pizzas, tires, ferris wheels, rings, steering wheels, cakes, pies, buttons, satellites, etc.
- So that scientists studying the planets can use circumference of
the planets to help compare the planets to their relative sizes and to each
other
- So that I can use my knowledge of radius and diameter to find
the area of a circle
- So that I can use my knowledge of radius and diameter to find
the circumference of a circle
- So that
an architect can precisely design arcs or buildings with a circular structure

### UNDERSTANDING THE STANDARD

- A circle is
a set of points in a plane that are the same distance from a point called the
*center*. - A chord is a
line segment connecting any two points on a circle. A chord may or may not go
through the center of a circle. The
diameter is the longest chord of a circle.
- A diameter
is a chord that goes through the center of a circle. The length of the diameter
of a circle is twice the length of the radius.
- A radius is
a line segment joining the center of a circle to any point on the circle. Two
radii end-to-end form a diameter of a circle.
- Circumference is the
distance around or “perimeter” of a circle.
An approximation for circumference is about three times the diameter of
a circle. An approximation for
circumference is about six times the radius of a circle.

### ESSENTIALS

**The student will use
problem solving, mathematical communication, mathematical reasoning,
connections, and representations to**

- Identify and describe the diameter, radius, chord, and
circumference of a circle.
- Investigate and describe the relationship between
- diameter and radius;
- diameter and chord;
- radius and circumference;
- diameter and circumference.

### KEY VOCABULARY

*Updated: May 29, 2019*