Circles, Semi Circles and Quarter Circles

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

• C = π r

• C = π d

• C = (π r)/2

• C = 2 π d

If you are given the diameter, how can you calculate the radius?

• Multiply the diameter by 2

• Subtract 2 from the diameter

• Add 2 to the diameter

• Divide the diameter by 2

How do you find the area of a circle?

• π d^2

• 2 π r

• 2 π r^2

• π r^2

A ____________ is half of a circle.

• Circumference

• Pi

• Semicircle

• Composite shape

The diameter =

• 8cm

• 16cm

• 4cm

• 10cm

The radius =

• 8cm

• 4cm

• 16cm

• 10cm

In this figure, d would =

• 8cm

• 16cm

• 4cm

• 10cm

Radius =

• 10cm

• 16cm

• 4cm

• 8cm

Find the ARC LENGTH of the semicircle.

• 20.56cm

• 12.56 cm

• 25.12 cm

• 6.28 cm

Find the perimeter of the semicircle.

• 12.86cm

• 20.56cm

• 25.12cm

• 50.24cm