Exploring Circumference and Area of Circles

What is the shape of a circle defined as in geometry?

• A two-dimensional square

• A set of all points in a plane at a fixed distance from a center

• A shape with equal radii

• A shape with unequal diameters

What does the diameter of a circle represent?

• The distance around the circle

• The length of two radii

• The distance across the circle through the center

• The distance from the center to any point on the circle

Tags

CCSS.HSG.C.A.2

What does π approximately equal to?

• 3.14159

• 22/7

• Both A and B are correct

• 2.71828

Tags

CCSS.HSG.GMD.A.1

Which formula is used to calculate the circumference when the diameter is known?

• C = πr^2

• C = πd

• C = 2r

• C = 2πr

Tags

CCSS.7.G.B.4

How do you calculate the circumference if only the radius is given?

• C = d/π

• C = πr^2

• C = 2πr

• C = πd

Tags

CCSS.7.G.B.4

What is the circumference of a circle with a diameter of 25 cm?

• 50π cm

• 12.5π cm

• 25π cm

• 78.5 cm

Tags

CCSS.7.G.B.4

How is the diameter found if the circumference is known?

• D = π/C

• D = C/π

• D = C/2π

• D = 2C/π

Tags

CCSS.7.G.B.4

What is the formula for the area of a circle?

• A = πd

• A = πr^2

• A = r^2/π

• A = 2πr

Tags

CCSS.7.G.B.4

What is the area of a circle with a radius of 21 feet?

• 42π feet squared

• 441π feet squared

• 1384.74 feet squared

• 21π feet squared

Tags

CCSS.7.G.B.4

If the diameter of a circle is 42 feet, what is the radius?

• 42 feet

• 14 feet

• 84 feet

• 21 feet

Tags

CCSS.7.G.B.4