ACHS Geometry - Circles

Parts of a Circle

100

The line segment from the center of the circle to it's edge.

Radius

200

"Twice the Radius"

Diameter

300

A line that touches a circle at one point.

Tangent Line

400

A line segment with both endpoints on a circle's edge, but does not necessarily go through the center.

Chord

500

"Half the Diameter"

Radius

Area

100

What is the formula for the area of a circle?

A = Pi*r²

200

What are the proper units for the area of a circle if the radius is measured in feet?

feet²

300

What is the area of a circle with a radius of 10m (answer in terms of pi with correct units)?

100 pi meters²

400

What is the radius of a circle whose area is 78.5 in²? (use proper units and round to nearest tenth)

5 in

500

Calculate the area of a circle with a diameter of 8 cm. (round your answer to the nearest tenth and use proper units)

50.3 cm²

Circumference

100

What is the formula for circumference of a circle?

C = 2*pi*r

200

What is the perimeter of a circle called?

Circumference

300

Rewrite the standard circumference formula in terms of diameter, d.

C = pi*d

400

Find the circumference of a circle with a radius of 17 m in terms of pi.

34 pi

500

Calculate the circumference of a circle with a diameter of 7 inches. (use proper units and round to nearest tenth)

22.0 in

Sectors

100

What is the proper name of the angle used to measure arc length in a circle?

Central Angle

200

A half-circle would correspond to what measure of the central angle?

180 degrees

300

DAILY DOUBLE!

Organize your team and decide what you would like to wager (0 - Current Score).

You will work as a TEAM and 15 SECONDS to answer the question.

A standard large slice of pizza corresponds to what measure for the central angle?

400

Find the arc length of a circle, with a radius of 5 cm and a central angle of 60 degrees. (use proper units and round to nearest tenth)

5.2 cm

500

Find the sector area of a circle, with a radius of 7 cm and a central angle of 80 degrees. (use proper units and round to nearest tenth)

34.2 cm²

Pi

100

What is the symbol for pi?

pi (insert pi greek symbol)

200

Name pi rounded to 2 decimal places.

3.14

300

What are the units for pi?

Pi is unitless

400

Explain what pi represents.

Pi is the ratio of a circle's circumference to its diameter.

500

DAILY DOUBLE!

Organize your team and decide what you would like to wager (0 - Current Score).

You will work as a TEAM and 15 SECONDS to answer the question.

What classification of numbers does pi belong to?