Equations of Circles

What is the formula for circumference of a circle given the diameter?

• C = π r

• C = 2 π r

• C = π d

• C = 2 π d

If the circumference of a circle is 44 π feet, what is the radius?

• 22 ft

• 44 ft

• 33 feet

• 3.14 feet

Name the circle part shown

• Arc

• Sector

• Chord

• Radius

Find the m∠PQS.

• 44⁰

• 65⁰

• 71⁰

• 130⁰

Name the circle part shown in red

• Diameter

• Radius

• Sector

• Tangent

what is the area of this semicircle ?
d = 8 cm 

• 100.48 cm²

• 80 cm²

• 200.96 cm²

• 25.12 cm²

Find x.

• 84⁰

• 42⁰

• 21⁰

• 168⁰

What is the standard form of the equation of a circle with center at the origin and radius r?

Which of the following represents the equation of a circle with center (h, k) and radius r?

• 5

• 10

• 25

• 50