Circle Geometry Concepts

Miss White teaches seventh graders about calculating the area and circumference of circles and semi-circles. The lesson includes examples of finding the area of a semi-circle using a given diameter, determining the area of a circle from its circumference, and an exercise on calculating the area of a circle with a given diameter. The lesson emphasizes the use of pi approximated as 22/7 and involves drawing diagrams to aid understanding.

What is the approximate value of pi used in this lesson?

• 3.142

• 3.14

• 3.14159

• 22/7

If the diameter of a semi-circle is 14 cm, what is the radius?

• 14 cm

• 7 cm

• 28 cm

• 21 cm

How do you calculate the area of a semi-circle?

• 1/2 * pi * radius^2

• pi * diameter

• 1/2 * pi * diameter

• pi * radius^2

What is the formula for the circumference of a circle?

• pi * radius^2

• 2 * pi * diameter

• 2 * pi * radius

• pi * diameter

Given a circumference of 24 pi cm, what is the radius of the circle?

• 6 cm

• 48 cm

• 24 cm

• 12 cm

What is the area of a circle with a radius of 12 cm?

• 72 pi cm^2

• 288 pi cm^2

• 24 pi cm^2

• 144 pi cm^2

If a circle has a diameter of 42 cm, what is its radius?

• 14 cm

• 84 cm

• 42 cm

• 21 cm

How do you find the area of a circle using its radius?

• 2 * pi * radius

• pi * radius^2

• 1/2 * pi * radius^2

• pi * diameter

What is the area of a circle with a diameter of 42 cm using pi as 22/7?

• 1260 cm^2

• 1320 cm^2

• 1440 cm^2

• 1386 cm^2

What is the first step in finding the area of a circle when given the diameter?

• Square the diameter

• Multiply by pi

• Use the circumference formula

• Find the radius