Circle Geometry Concepts

This video tutorial reviews how to calculate the circumference and area of a circle. It explains two formulas for circumference: C = 2πR when given the radius, and C = πD when given the diameter. For area, the formula A = πR² is used, requiring conversion from diameter to radius if necessary. The video provides examples using both radius and diameter, demonstrating calculations in terms of π and rounded values. Students are encouraged to practice these calculations.

What is the formula for calculating the circumference of a circle when the radius is known?

• C = πD

• C = 2πR

• A = πR²

• A = 2πD

If you know the diameter of a circle, how can you find the radius?

• Subtract 2 from the diameter

• Square the diameter

• Multiply the diameter by 2

• Divide the diameter by 2

Given a circle with a radius of 7 inches, what is the exact circumference in terms of π?

• 14π inches

• 7π inches

• 49π inches

• 21π inches

What is the rounded circumference of a circle with a radius of 7 inches, using π ≈ 3.14?

• 21.98 inches

• 43.96 inches

• 44.96 inches

• 22.96 inches

For a circle with a radius of 7 inches, what is the exact area in terms of π?

• 28π square inches

• 14π square inches

• 7π square inches

• 49π square inches

What is the rounded area of a circle with a radius of 7 inches, using π ≈ 3.14?

• 154.86 square inches

• 152.86 square inches

• 153.86 square inches

• 150.86 square inches

What is the formula for calculating the circumference of a circle when the diameter is known?

• A = πR²

• A = 2πD

• C = πD

• C = 2πR

Given a circle with a diameter of 50 cm, what is the exact circumference in terms of π?

• 50π cm

• 25π cm

• 100π cm

• 75π cm

What is the rounded circumference of a circle with a diameter of 50 cm, using π ≈ 3.14?

• 160 cm

• 150 cm

• 157 cm

• 155 cm

For a circle with a diameter of 50 cm, what is the exact area in terms of π?

• 125π square cm

• 500π square cm

• 250π square cm

• 625π square cm