1. Test is next class Test is open note
Circle review
Test is next class
Test is open note

2. Find the area and circumference of the circle below that has a radius of 8.5 cm.
𝐴=𝜋 𝑟 2
𝐴=𝜋∗ 8.5 2
𝐴=72.25𝜋
𝐴≈ 𝑐𝑚 2
𝐶=2𝜋𝑟
𝐶=2∗𝜋∗8.5
𝐶=17𝜋
𝐶≈53.41𝑐𝑚
8.5

3. Inscribed angles 1. 3𝑥−3=120/2 3𝑥−3=60 3𝑥=63 𝑥=21 ∠𝐵=180−50−70 ∠𝐵=60°
𝑥−3=120/2
3𝑥−3=60
3𝑥=63
𝑥=21
∠𝐵=180−50−70
∠𝐵=60°
Arc AC=60*2
Arc AC=120°
Arc CBA =360°−120°
Arc CBA =240°

4. Circle vocabulary Minor arc Central angle radius Inscribed angle
Tangent line
diameter
chord
semicircle
Major arc

5. More inscribed angles 𝑥= 58+106 /2 𝑥=82° 𝑦=(360−58−106)/2 𝑦=98°
𝑧=180−93
𝑧=87°

6. Length of intersecting chords
3𝑥=6∗4
3𝑥=24
𝑥=8

7. Area of a segment Segment = sector –triangle sector:
𝐴= ∗𝜋 ∗24 2
𝐴= 1 3 ∗𝜋 ∗24 2
𝐴=192𝜋≈603.19
Triangle:
𝐴=.5∗𝑠𝑖𝑑𝑒∗𝑠𝑖𝑑𝑒∗sin⁡(𝑖𝑛𝑐𝑙𝑢𝑑𝑒𝑑 𝑎𝑛𝑔𝑙𝑒)
𝐴=.5∗24∗24∗sin⁡(120°)
𝐴≈249.42
Segment: 𝐴=603.1∗−249.42= 𝑢𝑛 2

8. Length of a chord
Step 1: connect end points of chord to center of circle to make a triangle
Step 2: WZ=XZ=20/2=10
Step 3: angle Z= 130
Length of chord: choice 1= law of cosines
𝑊𝑋 2 = −2∗10∗10∗cos⁡(130°)
𝑊𝑋 2 =328.56
𝑊𝑋=18.13
Choice 2= law of sines:
Angle W= ( )/2=25
𝑊𝑋 sin⁡(130°) = 10 𝑠𝑖𝑛25°
𝑊𝑋=(10𝑠𝑖𝑛130)/𝑠𝑖𝑛25
WX=18.13
Length of chord WX

9. Equations and graphing circles
Identify the center and radius on the equation below and then graph it on a separate sheet of paper.
(𝑥−4) 2 + (𝑦+2) 2 =16
Center= (4, -2)
R=4