Geometry Honors: Unit 10 Day 1 Circles and Circumference, Measuring Angles and Arcs

!Circle: A circle is is the set of all points in plane that are equidistant from the center. !!!!!!!!!!!!!!!! !!1. Name the circle and identify a radius. !!!!!!!!2. Identify a chord and a diameter of the circle. !!!!!

Learning Target - A circle is is the set of all points in plane that are equidistant from the center. Circumference is the linear distance around the edge of a circular object. The arc of a circle is any connected part of the circle.

Success Criteria: *I can identify and use the parts of a circle. *I can solve problems involving the circumference of a circle.   *I can identify central angles, major arcs, minor arcs, and semicircles, and find their measures. *I can find arc lengths.  

3. If RT = 21 cm, what is the length of " ? !!!!!!!!!!!!!!!!!!!!!!!4. The diameter of " X is 22 units, the diameter of " Y is 16 units, and WZ = 5 units. Find XY. !!!!!!!!!!!!

QV

⊙ ⊙

5. The diameters of " D, " B, and " A are 4 inches, 9 inches, and 18 inches, respectively. Find AC. !!!!!!!!

Circumference: The circumference of a circle is the distance around the circle

6. A series of crop circles was discovered in Alberta, Canada, on September 4, 1999. The largest of the three circles had a radius of 30 feet. Find its circumference rounded to the nearest tenth of a foot.

" !7. Find the diameter and the radius of a circle to the nearest hundredth if the circumference

of the circle is 65.4 feet. !!!!!!!!!

⊙ ⊙ ⊙

8. Find the exact circumference of " K. !!!!!!!Central Angle: A central angle of a circle is an angle with a vertex in the center of the circle. !!!!!!!!!!1. Find the value of x. !!!!!!!!!Arc: An arc is a portion of a circle defined by two endpoints. !!!!!!!!!!!!!!

⊙

2. is a radius of C. !a. Identify as a major arc, minor arc, or semicircle. Then

find its measure. !!!b.Identify as a major arc, minor arc, or semicircle. Then

find its measure. !!!c.Identify as a major arc, minor arc, or semicircle. Then find its measure. !!!!!!!!!!!!!!3.Refer to the circle graph. !a.Find .

!!!!b. Find . !!!!!!!!

WC ⊙

XZY∩

WZX∩

XW∩

mKL∩

mNJL∩

4.a. Find in M b. Find in M. !!!!!!!!!!!!!!!!!!!5. For each of the following figures, find the length of . Round to the nearest hundredth.

mLHI∩

⊙ m IJK∩

⊙

DA∩

a. !

� !!!!!!!

b. !

�

c. !

�